Category: Uncategorized

Are you a silent carrier?

I was requested by my IVF doctor to have my genetic carrier state screened. However I had some doubt whether it is necessary – when I had my first baby my OBGYN already tested me for 5-6 genetic carrier status and I was all negative. The kit the IVF clinic uses includes nearly 300 single genetic diseases but most of them have higher incidence in other ethnic groups but not mine. When I expressed disagreement that I don’t really need this “expanded carrier status” screen, she mentioned that I could have thalassemia carrier status and also I could have X-linked recessive genes so to convince me that even my husband’s genetic tests were all negative I still have to worried about whether I have X-linked recessive genes, which could be passed to male progeny only).

However thalassemia itself could have cues on your CBC and hemoglobin electrophesis results, which are routine tests for pregnancies in the US and I was screened when I had my first kid.

I checked NEJM has published a population screening study in Hong Kong:

https://www.nejm.org/doi/full/10.1056/NEJM199705013361805

“Of the 2420 students who attended the informational meetings, 1812 (75 percent) obtained parental consent and agreed to undergo screening. A total of 1800 blood samples were obtained and analyzed (12 students were absent from school on the days on which phlebotomy was scheduled).

One hundred fifty of the 1800 blood samples (8.3 percent) had microcytosis (mean corpuscular volume of less than 80 μm3). These 150 blood samples were tested for α- and β-thalassemias and iron deficiency. The α-globin genotypes of all 150 blood samples were determined both by Southern analysis and by PCR with primers specific for the (–SEA) type of α-thalassemia deletion. Mutations in the β-globin gene clusters were determined only in blood samples with hemoglobin A2 concentrations above 3.5 percent.”

The study itself did not approve that if your MCV is normal then you don’t have thalassemia genes. For this purpose, you’d have to collect a group of patients known to have thalassemia genes and test their MCVs and even if one of them have normal MCV then MCV itself can not be used as an absolute screening tool for rule out, but it is a pretty good indicator for whether you have thalassemia. See this study:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3920506/

“…seven-hundred and twenty two patients presenting ten different α-thal genotypes were considered. All patients (N=722) showed reduced MCV and/or MCH values…”

  1. genetic test should be recommended according to patient’s ethnic groups
  2. genetic counseling should be conducted before ordering the genetic tests for patients to understand the risks and benefits and the necessity
  3. some genetic disease could be screened with some much simpler tests such as CBC and hemoglobin electrophoresis instead of genetic tests.

Is that possible that you missed a STEMI?

When I was in medical school or even in my residency, my thought was like – oh, you can’t miss a STEMI, it is just too obvious to be missed. But the truth is that it is very possible to miss a STEMI and actually in real life, many STEMIs have been missed. The reasons why STEMIs are missed:

STEMI EKG changes can be transient. Once I thought after STEMI the EKG should go down the route of showing q waves etc, but sometimes STEMI EKG can go back to normal looking. So if somehow the STEMI EKG is not cited or not seen or misplaced (oh those paper EKGs flying everywhere…), the diagnosis is missed. I remember where I was trained, ER attending always have to sign the EKG with date/time and their name, a really good practice indeed to make sure every EKG is read by an attending. While on the floor, we don’t have this kind of practice or habit, so I did encounter a case that the EKG done during a rapid response was later found to have clear patterns of STEMI.

Secondly, as you all know there are STEMI equivalents and posterior MI. Sometimes V2-V3 elevation could mimic early repolarization pattern. Single avR elevation. With some residency program hosted by a hospital without a cardiac cath lab, most of these patients are screened and shipped to somewhere else, and residents are not exposed to as much high-risk EKGs as they should.

When to call consults for your patient

This is a big headache for hospitalists – when to call consults. I have seen crazy practices such as calling consults for every single issue the patient has, oh you have COPD and p/w SOB, let’s call pulmonary. But what is more common in the daily clinical practice is that the consults will tear you apart if they think you are calling unnecessary consults and if you somehow miss something and the consult will also come to tear you apart – why you didn’t call me earlier? Leave some safety margin and smell the smoke before it becomes a fire.

Now people think you should call consult only when it is necessary. Is it true? The judgment of when it is necessary solely depends on your understanding of the case and you are only a generalist and you may not even have the knowledge to tell when it is necessary. This fundamental paradox seemingly cannot be overcome and is the root cause of the conflicts between generalists and specialists – the best solution I have seen is to trigger a consult automatically when the case meets certain criteria and these criteria can be discussed beforehand with the specialists. Or you can curbside.

Curbside vs. Formal consult: do not trust a curbside consult fully – things can go wrong in many ways. The information you give to the consult might not be sufficient for him/her to make the best clinical judgment – the way you describe the case might not be right due to your own blindspot BECAUSE you are not as educated as the consult with the issue at hand.

Sometimes, the person you curbside might be only a fellow/PA/NP instead of the attending on the service, would you trust that clinical opinion? I would not. (I had a case with low baseline cortisol level and normal cosyntropin response and the endocrine fellow let the patient go).  Last but not least, if their name if not on the chart, they care less than when their name is on the chart. Some good ones may tell you hey this is s tricky case do you mind putting in a formal consult and I will see the patient later; but sometimes it just happens that everyone is busy.

Last caveat: if you feel like once you call a consult and they come to see your patient, your job is done, then you are totally wrong. Consults miss things all the time. There was one time I had a patient with bacteremia and asked ID consult where is the source (twice!) – he documented in the note that the patient had some IV a few weeks ago and likely has phlebitis. On the day of discharge, patient said he had neck pain and steroid injection to his neck a few days before he was admitted! Of course, I rushed him to the MRI for a scan.

Interesting case this week

– heart murmur is only heard when patient has ECHO done

– STEMI is only diagnosed when troponin is going up – a young male presented with typical unstable angina symptoms and ED noticed Inferior leads 1mm ST elevation and reciprocal ST changes on precordial leads but cardiac cath lab refused to take him stating those were early repolarization. Later troponin keeps going up from 0 to 0.05 to 0.13, then rushed to cardiac cath…

– how to dose warfarin if liver failure and INR already 2?