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Is the new professionalism and ACP's new ethics really just about following guidelines?

The Charter ( Medical Professionalism in the New Millennium.A Physician's Charter) did not deal with just the important relationship of ...

Saturday, February 18, 2023

Here is how a physician can be a steward of health care resources

I knew from the first day of medical school that this doctor business was not going to be easy. We were told how many newwords and and concepts we had to master in the next few months,how some of us would not make it and how as physicians -if we even made it that far-would continues to have to work hard to continue to master new information and techniques.

As the years went by medical school, residency, fellowship all had their share of difficulty concepts to master and there was always something else to learn - always the perception that you needed to known all you could as you had people's health and lives in your hands.The rewards could be great but so were the challenges and the continuing obligation.

But then with the publication of the Physician Charter,the new medical professionalism,things seem to get even harder as a new daunting task appeared on the scene. Now doing your best for your patient to live up to your fiduciary duty was not enough, you also had to work for social justice and be a steward of society's finite medical resources.

Wow, that certainty didn't sound easy. In fact I had no clue as to how to live up to that new obligation nor understood  exactly what these those terms even meant and was it not the case that sometime an individual's best interests conflicted with those of society assuming that the later interests could even be appropriately defined.

It was years later when I finally realized how I could live up to these new ethical obligations an exemplify the traits expected and demanded of a professional in the new milimeum and now it seems very easy.

It is easy because the medical progressives,the elite,the thought leaders , the hierarchy of various medical professional organizations will make it easy for the rank and file medical practitioners in the field. These leadesr will determine what is of value not only to the patients but to society. So based on what is high value guidelines will be forthcoming and the field docs will only have to adhere to them to do what is right for the patient which will also be what is in the best interests of society.

 Any concern that I might have had about some conflict between the interests of the individual patient and society will vanish because as Victor Fuchs has told us what is good for the group will necessarily have to be good for your patient as well as he is a member of the group which is benefited. It gets better. The tests or procedures that you deny your patient is now understood to not be rationing at all. This is the case because some of the members of ACP elite has wisely redefined rationing as restricting the use of effective,high value care. So restricting lower value are is not by definition rationing at all.

This important role of determining what is high and what is not high value care is not the slam dunk that some members of the USPSTF task force said in regard to their pronouncement of no need to do any PSA screening. No this type analysis requires specialized expertise and training and is "typically performed by investigators", ( such as those writing the above referenced Annals article) 

Wednesday, February 15, 2023

How do we know what is right? Easy do a meta-analysis

After all the cochrane group says that in regard to establishing scientific truth the "systematic review of all relevant randomized clinical trials is the highest level of evidence."

What seems to be a different view is that the following characterization of the MA by Dr.Steven Goodman who explains that a MA is basically an observational trial in which the subjects are themselves clinical trials. In the traditional hierarchic of clinical evidence observational trials are not considered the top of the pyramid.

so what is it-the highest order of evidence or merely a lowly observational study?

What does "impaired relaxation" on echo report mean and what to do about it

Half of the patients labelled as having  heart failure are designated as "diastolic heart failure" or HFpEF,  the currently prefered medical jargon for heart failure with preserved ejection fraction. The other half of HF patients have heart failure with reduced ejection fraction or HFrEF.

Both categories are creatures of the echocardiogram.The ejection fraction or EF is the ratio of the stroke volume to the volume of blood in the left ventricle at the end of diastole.Diastolic dysfunction is defined by various combinations of other echo measurements, that relate to how easily blood flows into the left ventricle during the ventricular filling phase aka diastole and strive to be clinically useful indicators of an elevated left ventricular filling pressure (EDLVP)

It seems to be the case that as humans age the blood flow less easily into the left ventricle due to a number of related and as always in medicine or biology poorly understood factors.These include the capacity of the ventricle to relax after ejecting the blood in systole,how stiff or compliant the ventricle is,the geometry of the ventricle, how well " restoring forces"  (aka elastic  recoil) - THINK HERE OF COmPRESSING A TENNIS BALL AND THEN RELEASING THEFORCE AND BALL POPS BACK IN SHAPEwork and the restraint of the pericardium.The key distinguishing characteristic of an elite endurance athlete is impressive diastolic filling.

Ventricular  diastole flow is typically considered to have two phases-the early rapid filling phase and the later phase brought about the contraction of the atria.These stages can be visualized and quantitated by placing an echo probe of the the mitral valve and measuring the velocity of early flow  (the E wave) and the late wave (the A wave) and if we have two numbers someone will make a ratio.

The ratio of the early velocity to the late velocity ( E/A ratio) is a simple measure of diastolic function.With aging early flow decreases (  generally thought to be due  in early diastole to impaired relaxation and loss of elastic recoil) resulting in a lower E/A ratio. This is considered to be the earliest stage of diastolic dysfunction in which diastolic flow is decreased but cardiac filling pressures have not significantly increased. As ventricular filling become more impaired pressure builds in the left ratrium so that early flow increases as does the E/A  restoring a normal appearing a pattern labelled as "pseudonormal" ( this stage is now referred to as "stage one " in the 2016  American Society of Echocadiography and the older terms for the more severe stages of diastolic function,pseudonormal and restrictive have also been replaced with stage 2 and stage 3.)

Not only can diastolic flow across the mitral valve be measured by echo so can the movement of the supporting tissue of the mitral valve ( mitral annulus). The early movement , coincident with the E wave is labelled e prime and the late movement a prime.
But what to about echo reports that state impaired relaxation.Is it "normal for age" or a possible percursor to HFpEF.is there any role for aerobic exercise to lessen progression to HFpEF?

Is medical ethics a social,historical or economic artifiact?

The title question was raised in an article published in the Journal of the American Medical Association in 1995 by dr. Edmund D. Pellegrino (JAMA,may 24/31, 1995 -vol 273 no 20.)The article was entitled "Medicine and the Holocast:Learning more of the Lessons."

Pelegrino explains that the idea that the German war crimes perpetrated by physicians ( at least people with a medical degree) were the acts of only a handful was wrong. Many more physicians were involved in the what transpired under Nazi rule. He quotes historians who have demontrated how pervasive was the corruption and the degree to which German physicians "began to elevate service to the state above medical ethics"

Saturday, February 11, 2023

Is the ACP's notion of value centuries behind current economic tought?

Is value subjective? Is value derived from the labor going into a good or service? Do business owners exploit their employee by stealing their "surplus value"? Why do diamonds cost more than water while water is necessary for life?

The value theory of value was promoted by David Ricardo and bought into and popularized by Karl Marx.

However, in the late 19th century three economists developed economic theory that became known as the marginal revolution. Value,they said was not something inherent in the object but value results from the subjective evaluation of the person and that evaluation is made at the margin. For example, if you have 20 apples you are likely to value the 21st apple less.

Tales of "corporate medicine"- care delayed may equate to care denied

 In this essay I will describe how the evaluation of a medical problem seems to work in at least one large not for profit big city hospital system and how that differs from how it used to be in a physician owned fairly large internal medicine practice in the same big city.

The basic events described are true but some non-essential details are altered in the following  narrative  to shield the identity of the innocent and the not so innocent. 

William G,a retired 78 year old accountant  has a routine annual visit with his primary care doctor who is a board certified ( and re certified ) internist.WG thought it was an annual exam but in reality, it was a modified Annual Wellness Visit (AWV) in which there was no physical touching involved between patient and physician. WG's red blood cell count was reduced from the previous year and the iron studies were done and they were consistent with ( but not diagnostic of) iron deficiency anemia. Based on his age a GI workup ( ie upper and low GI endoscopy) was in order and WG set off to get an appointment with a GI doctor in the same hospital system who had done a coloscopy for WG three  years earlier. Although he was an established patient it was 3 week before an office visit could be scheduled and the another 5 weeks before the endoscopy procedure could be scheduled, a frustrating 2 month delay.

When I was in internal medicine practice in the 1970s in a physician owned group the time from one partner having a patient needing a GI endoscopy to seeing one of the GI docs in the group would have been one or two days at the most and the procedure would have been scheduled in another one to three days at most. 

In the private practice group the clinic administrator worked  for the doctors and in the large big hosptial system to some degree it is the other way around.The staff who do the scheduling are hired by the hospital and work for the hospital 

Do the arguments of Kenneth Arrow and William Baumol forclose Market solution provison of health care

The overly long tittle  refers to Kenneth Arrow's information asymmetry argument against fee for service in health care? Does "Baumol's Cost Disease" lead to the conclusion that health care must be paid for by the goverment through taxes?

In regard to Baumol's disease, it is far from the case that his formulation is unchallenged. Baumol makes a number of simplifying assumptions and aggregations in his model most of which have been seriously critiqued. For example see here for an excellent detailed economic  analysis of his assumptions and his logic and analysis. But as usual the headlines are on page one and the clarifications and retraction are found buried much deeper in the paper in smaller type .

Still more ways to cook the clinical trial books

Clinical trials are concerned with efficacy and safety. There are statistical tricks and methodologic manuevers than can be used to either give the illusion of safety when that has not been proven by the data and/or likewise give the appearance of efficacy or equivalence with a comparison drug when the data does not really allow for that conclusion. Some of these methods are intuitively obvious-once they have been pointed out-others are more subtle and require a degree of sophistication not typically possessed by the average physician and at a level not likely to be taught to most medical students.

Here are some of the simple ones :

use a dose of the comparison drug that is too low(or too high) depending it you are trying to show equivalence or superiority or comparing side effects

in a comparison trials -keep the power low by have a relatively small trial

measure multiple endpoints but report only those that are favorable

use sub-group analysis to find a set of patients in whom there appears to be efficacy

arrange multi-center trials reporting those results from centers in which the right answer is found

cherry pick the subjects to minimize likelihood of side effects

report composite end point results when demonstration of efficacy is the aim and report individual safety outcomes when safety demonstration is the aim

Is the internist as the "doctor's doctor" no longer existence?

 In the days when I trained as an internist and for another 20 years or so after that medical folks talked about the doctor's doctor. This referred to an internist known for his meticulous history taking skills and performing a very complete physical exam that would at least sometimes find something others has missed, He (and it was not always a he) was the physician to whom other doctors would refer to when they or their family member had a serious or mysterious medical condition or maybe just for reassurance. 

However, as time went on the monetary compensation of the internists shrunk to a point (where for example they make only slightly more than a CRNA) and there was no time to take the time the oldtimey internist took because they could not afford to.Less compensation per patient lead to more patients per hour needed to be seen.

Recently I learned of an encounter a relative living in France had with his internist.At least there is one internist in France who seems much like that idealized internist that my fellow internal medicine residents and I hoped we could become.

My relative had been the victim of a missed acute appendicitis and was now several weeks post  percutaneous drainage of several abscesses secondary to a ruptured appendix and was awaiting a follow up appendectomy 

The internist took very detailed history and examined him and agreed with the need for follow up appendectomy and gave him the names and backgrounds of several surgeons.

Senior internists in France earn about $21200 per year only slightly less than US general internists but graduate from medical school without significant debt and have low malpractice premiums and are largely free of the major hassles of insurance approval for testing.Perhaps their practice styles allow them more time to be more like the stylized internist model of the past in the U.S.Alternately perhaps my relative's internist was an aberration.  


'I knew much more then than I do now"

A few years ago I spent some time doing "well baby" exam on employees and the executives of a large international company. The emphasis was on prevention or "preventative" (this had become a real word) medicine.

"Determining" the risk of a heart attack for an individual patient was routine.Determining  is in quotes because that seems to be a verb to use to magnify or exagerate the imporance or validity of what may be an educated or partially educated guess or even something less valid than that i.e. something you just make up.

do endurance athletes live longer beause of voluminous exercise or because their genes predispose them to high 02 oxygen uptake in later years?

If data show that endurance athletes live longer than non endurance athletes is it  so because of the life prolonging effects of endurance exercise performed over many years or is it the case that the endurance athletes genetic inheritance allows them to not only run long and fast but to survive longer. By survive longer I mean in part that for example  an octogenarian with an 02 maX of 30 is more likely to withstand the physiological trauma of septsis or major trauma better than an age cohort with an 02 max of 19.

A person',s maximal oxygen uptake(v02Max) is a strong predictor of life  expectancy. A major part of frailty in the elderly  is a low 02 max.

Tuesday, February 07, 2023

LGE in long time endurance athletes may not mean a potentially arrhythmogenic scar

 Late gadolinium enhancement (LGE) in long time endurance athletes may not mean scar tissue  (in the sense of replacement scar tissue ) and may represent a "benign" finding.All LGE may not mean  the same type of tissue alteration.That particularly applies to LGE at the insertion points of the right ventricle (RVIP).

 See Grogoratos,c clinical importance of late gadolinium enhancement at right ventricular insertion point Int J cardiovascular imaging 2020 .

  and Shambhag SM et al https://academic.oup.com/eurheartj/article/40/6/529/5185127

"... LGE at the RVIP ( right ventricular insertion points) has been proposed to represent focal plexiform fibrosis (associated with myocardial disarray rather than replacement fibrosis"  Bravo, PC, Late gadolinium enhancement confirmed to the right ventricular insertion points in hypertrophic cardiomyopathy an  intermediate stage phenotype, European heart journal cardiovascular imaging, 2016 Mar 17(3) 293  /// this article references the following as the source of the plexiform fibrosis pattern 

One key question is  does plexiform fibrosis pose the risk of inciting an arrythmia that does replacement fibrosis.  

 See also Moor, JC, The histological basis of late gadolinium enhancement in cardiovascular magnetic resonance imaging  in hypertrophic cardiomyopathy. Amer Coll cardio 2004 43 2260 

Does the classsification of atrial fibrillation need to be revised?

I think so , here is why,

 Paroxsymal atrial fibrillation  (APF) is currently defined a a spontaneous remitting episode of atrial fibrillation (AFIB) lasting less than seven days and resolving without intervention. Current U.S. guidelines recommend oral anticoagulation therapy (OAC) for patients with all types of afib based on the stroke risk estimate using  CHA2DS2-Vasc score.

Modern pacemakers (PM) can now record tracings continuously and store them for long periods of time. Several studies have analyzed these tracings and we have learned that commonly PM patients have short runs of Afib,( or more accurately  atrial high rate episodesAHRE-some of which are in fact  not AF)  varying greatly in duration and frequency .

It does not make sense to assume we should have the same prognostic concerns  and therapeutic recommendations   to someone with a episode of afib lasting one minute as to  someone with afib lasting  five days without good data validating that position.

Several studies have attempted to correlate these runs of afib with stroke  rate. With one exception data  (see footnote 1) have not been analyzed if these episodes last less than 5 or 6 minutes.These studies have shown that there is a  coarse grain dose response relationship  between duration or  "burden" of afib and stroke risk. Attempts have been made to determine an afib burden level above which there is a significant increase in risk worth of initiating anticoagulation  and no consensus has been reached.

Various investigations have yielded different burden levels .

The ASSERT trial is widely quoted as showing a two fold increase in stroke risk for episodes of afib last over  6 minutes. See footnote 2 for a discussion of the surprisingly and diametrically  different ways these results were described in medical publications.

Yet another article discussing ASSERT  claims that a fib greater than 24 hours does have increased risk of stroke but for shorter episodes no statistically significant relationship was shown.


 1. The Rate Registry study reported no increase risk of stroke for afib duration episodes less than 10-20 seconds.But what about those episodes between 20 seconds and six minutes?

2. Chin-Scarabellit et al including senior author K. Ellenbogen  describe the ASSERT trial simply as showing  an increased hazard ratio (HR) even though it was not statistically significant while Conn  et al  say "surprisingly,no correlation was found in the ASSERT between AHRE (atrial high rate episodes) and a history of stroke" and speculated that this might have resulted from the fact that the sampling period was only the first 3 months after PM implantation. A third spin on the ARREST was offered by Dr B P Knight (EPLab Digest March 2012) who said that only the  highest quartile of duration ( more than 18 hours) was statistically significant.He did not discuss the problems involving in relying on subgroup analysis to reach a conclusion regarding outcome validity less alone  making therapeutic decisions on that basis. Data is often hard to obtain but sometimes  the real difficulty is in finding agreement as to what the data signify.

The demise and possible impending death of internal medicine

I can remember when being an internist was a really big deal. You were consulted on complex ,complicated cases and frequently some of whom were critically ill. In the city where I practiced , lets call it Metropolis,internists  were frequently the physicians to whom general practice physicians in outlying cities would send their patients who were very sick when they did not know either what was wrong with them or what to do (or if it was Friday afternoon on the weekends whenyou were not on call)

We used to complain abaout the Friday afternoon late call about from Dr. Brown who asked if could transfer Mrs Jone to your hospital. We were specialists and in an earlier era we were called diagnosticians .

Thee once was a organization called the Metropolitan Society of Internal Medicine. In its day there were several hundred members and monthly meeting were very well attended, often approaching 100 attendees. Membership  was not open to anyone who called himself an Internist, you had to be Board Certified or Eligible to apply and there was a membership committee who oversaw the approval process.

I remember the last meeting I attended whee the members and guests were seated a one long table seating about 15 people. Today there is no such society.

I recently  scanned the County medical society bulletin and say many other societies listing their dates for meetings.The internists society was no longer listed.

Libertarians and egalitarians both favor equality of opportunity but have different concepts of opportunity

Some (many?) conservatives and libertarians seem to think that they favor equality of opportunity while the progressives or egalitarians favor equality of outcome. Not so, the egalitarians say that they too favor equality of opportunity not outcome.

 Their view of opportunity includes the following consideration. If someone is ill,or poor or has some disability then they cannot enjoy equality of opportunity. A chronically debilitated,poor person does not have the same opportunity to obtain employment or get health care insurance or buy nutritious good or decent housing. Just as the modern day liberals ( progressives) have co-opted  the term liberalism from the use of the word  as in classical liberalism (now libertarianism), they seem to have co-opted equality of opportunity to mean much more than equality under the law which is typically the sense in which libertarians and conservatives  use the term.

The egalitarian ethic is not just an abstract principle but an imperative to do something about the inequality of  opportunity. Charity would be one method of mitigation of inequality but while many sincere progressives and egalitarians volunteer and contribute to charities their broader solution is government enforced redistribution of resources to lessen whatever inequality that is of particular concern at that time.

Here , of course, is the area  in which conservative and libertarians and  progressives part company  and it becomes clear that the opposing groups do not seek the same rules of society.They both may favor equality of opportunity but mean different things by the word.

Now what about the term social justice?

To the progressives social justice means taking action to mitigate instances in which there is unequal access or unequal opportunity that is brought about by many societal factors , such as poverty  and poor public schools.

 The classical liberal concept of justice is the securing to individuals a domain in which they are protected from interference from others and from agencies of the state while Rawls et al  maintain  that limited view of justice does not recognize "that distributive shares ..are often determined by factors that are "arbitrary" from a moral point of view,eg the inheritance of certain factors, intelligence ,strength ,social advantage,wealth  that are just the luck of the draw and the recipients are not deserving of those advantages. even if they work hard and use those advantages well those accomplishments are still arbitrary from a moral point of view.As Hayek said, the term justice does not need a modifier.

Wednesday, February 01, 2023

The unexpected relationships between both high dose statins and high level endurance exercise and coronary calcification

 The jury  has been back for a quite a while. Statins decrease the risk of coronary artery events. The curvilinear relationship between exercise and coronary artery events is also apparently beyond debate.

So one would not predict that both statins and exercise could be too much of a good thing in regard to coronary artery disease. Remember coronary calcification is, by defintion,coronary artery disease. 

There are ample data demonstrating that long time and high dose statin use  may increase the development of coronary calcification.In addition,there are reports of increased coronary calcification in long time marathon runners and endurance athletes. 

So,how does this work? Exercise at least  up to some level (that  level has yet to be defined) decreases CAD risk but at some level increases coronary artery calcification which is a marker of CAD. Is the calcification different in endurance athletes? There is evidence that in endurance athletes who have coronary calcification that there are more of the dense variety and less of the mixed type which is thought to be more likely to thrombosis. 

Can internists keep up with medicine

 I have sampled four internists , two in active practice two retired more than 10 years earlier.Perhaps we can excuse the ignorance in the retirees.

All were woefully ignorant about the basics of the most common cause of anemia in the world,Iron deficiency anemia (IDA).

Case in point. A 78 year old man is noted to have a decrease of more than one gram in his hemoglobin from the previous annual "wellness meeting" which should not be confused with the annual physical exam which at least for some perhaps many Medicare patients is a thing of the past.Medicare will pay for an  annual wellness visit but not a real hands on physical exam.  The internist who  practiced in a practice group associated with a large "not for profit" hospital system recommend he take ferrous sulfate three times a day,

Note- there was not at the time a recommendation for the patient to have a GI tract evaluation, not even a stool Guiac was mentioned. In 2019 a influential often quoted article by Ganz and Weiss included a flow sheet indicating that older patients ( over fifty) undergo a upper and lower endoscopy to rule out a source of bleeding if their initial blood tests has a pattern consistent  with ( but not necessarily diagnostic of ) iron deficiency anemiaThe patient 's blood test fit that pattern. This  pattern was low serum iron and percent saturation and a ferritin less than 100. Possible iron defeciency anemia in a man over fifty certainty warrants an evaluation for GI tract bleeding.

As the case evolved the GI doc's ignorance re IDA was revealed when he commented that a subsequent increase in the patient's ferritin reflected increasing iron stores. These two internists apparently knew little or  nothing about the iron regulating hormone,hepcidin,   If they did they would know how to administer oral iron and how to use the ferritin  ( and other tests suh as the Ferritin index )to help differentiate between IDA and anemia of chronic inflammation and their combination.

Medicare Wellness Visit will not detect early disease but it is quick easy money for internist

 For the past five years I have taken part in a version of the Medicare Wellness Visit with the addition of a series of blood tests.During that time a thyroid cancer grew to the size of a very large egg ( 5.5 cmX 3.5X 3.5) before it was finally detected from a cervical spine CT. Medicare Wellness exam is reimbursed by Medicare reasonably well but Medicare does not pay for physical exams

My medical " care " during  a nine month period during which I was ostensibly  being evaluated for a mild anemia is notable for the following:

1.The entry of a number of errors in my medical chart ( which is recorded in a widely used electronic health record (EHR) My diagnosis included atrial fibrillation and diabetes neither of which do I have.The EHR continues  to admonish me that my diabetic eye exam  and diabetic foot exam are  overdue.

2.The ignorance of my primary care doctor and a GI specialist  in regard to the diagnosis and treatment of  the most common anemia in the world namely iron deficiency anemia was not reassuring. Both of their  knowledge gaps could have been quickly corrected  by spending a few minutes accessing Up T0 Date on their  electronic device.

3.The alarmingly long time lag between various elements of my diagnostic workup which took place in a nationally known and highly ranked medical care system AKA hospital system. For example from the time my  thyroid cancer was diagnosed by a fine needle aspiration (FNA) until the day of surgery was 43 days.

4.Entries in my record of several "phantom" medical exams. By phantom I mean description of exams that were in fact not done but still attested to by the physician's electronic signature. Why do some many physicians put their signature to a cut and paste exam that was not performed? Do they know what they will say if asked at a future deposition 'Doctor, did you actually do a exam on Mr.Jones on such and such date? Do you routinely lie on the medical record? .During a nine month period I was seen in the office by physicians 8 times and none of them apparently even looked at my neck let alone felt my thyroid gland  though on several occasions a normal thyroid exam was recorded in the chart  ( ie. the phantom exam).

5.My bone marrow aspiration and biopsy was done by a NP who told me she had been taught the procedure by a hematologist only some several  months earlier. A noteworthy thing about the BM exam was the price charged ($ 23,000 ) by the hospital.

6.The thyroid mass was detected by a CT of the cervical spine ordered by a neurologist who never did notify me of the abnormality. Fortunately I was able to access the report and read of the finding myself. An earlier chest CT report did not mention a thyroid mass although it was clearly visible. 

7.Astonishingy an ENT specialist who did a fiberoptic office exam of my throat for evaluation of a cricopharyngeal bar recorded a normal neck exam including the comment that the thyroid was free of nodules did not  perform an exam of the thyroid at all. One week later the cervical CT showed a thyroid mass 5.5 cm in its largest dimension. I had to wait 6 weeks for that ENT appointment.

8.The pathology report of the surgical specimen of the thyroid tumor has a number of syntactical and transcription errors,likely representing inconsequential errors but IMO reflecting an alarming lack of proofing and professionalism.

(9 The attending surgeon and the consulting endocrinologist both  either misread the pathology report or did not understand the significance of the reported findings and both told me that it was a very low risk variation but after the case was presented to the tumor board both amended their evaluation and recommendations accordingly based on the microscopic findings.

Iron deficiency is common in endurance athletes

 Iron deficiency is common in strenuous exercise i.e in  endurance athletes.

In runners "GI iron loss"is frequently mentioned as a possible cause of the iron deficiency frequently observed in runners but those publications rarely describe or explain exactly what they mean by GI  iron loss. 

Do they mean that the incidence of well recognized causes of GI bleeding (colon cancer,polyps,peptic ulcer etc) are common in runners. I find little evidence of that.Perhaps the reference is to some  type micro bleeds. Or do they mean there is some physiological mechanism by which there is GI iron loss without gross GI bleeding  namely occult GI bleeding ( ie. normal stool color with a positive hemoccult test).

Actually there are data indicating occult GI iron loss  with at least  one  study with positive  guaiac tests post marathons and another  pre and post marathon  upper endoscopy study showed some small lesions in the stomach that could possibly cause small amount of blood loss.

There is a physiologic mechanism by which runners ( and other endurance athletes) loose blood in the GI tract.The mechanism is the sloughing off of iron loaded duodenal luminal lining cells (aka enterocytes) Actually this is a physiologic process that happens in everyone but is believed to be significantly increased in endurance athletes particularly runners because they may have more exercise induced hemolysis which in turn leads to more iron loss due to duodenal cell sloughing which is intensified by hepcidin release for exercise which traps the iron in the duodenal cells and the macrophages. Enteroyctes have short ( about 3 day) life span.

Here is an "as if"  story of how that might work. Strenuous exercise leads to the release of IL6 which in turn stimulates the release of hepcidin, the hepatic hormone that is the master regulator of iron absorption and transfer and storage. (The putative release of hepcidin by IL6 is not crucial to  the story  it is the release of hepcidin that is important ).Hepcidin blocks the release of iron from the enterocytes and from macrophages slowing down the transfer of recycled iron to the bone marrow. 

  The Assocation of iron deficiency and running is well discussed in the sports medicine literature and in the lay runners press but much less so the hematology journals.