Chiefs’ Inquiry Corner – 2/10/20

February 10, 2020

Being an outstanding physician and lifelong learner requires stoking the flames of clinical curiosity.  In Chiefs’ Inquiry Corner (CIC) we attempt to succinctly answer actual clinical questions that have been raised on the wards and in the clinics of NYU’s teaching hospitals.  Our answers are not meant to be all encompassing or practice changing but rather to serve as springboards for further exploration. For those of us with short attention spans, we hope CIC satisfies that craving for a morsel of knowledge in a digestible format.


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One of the many manifestations of severe vitamin C deficiency, also known as scurvy, is easy bleeding and bruising. Vitamin C, or ascorbic acid, serves as a cofactor in collagen synthesis. Deficiency leads to impaired collagen formation, which results in vascular fragility. When considering the differential diagnosis for bleeding disorders, remember that coagulation factors released after vascular injury play an important role in hemostasis!

References:Vitamin C and Bleeding  
As of February 2019 the Infectious Disease Society of America HIV/AIDs guidelines no longer recommend starting all patients with a CD4 count <50 on primary MAC prophylaxis. There are two reasons for this update; one, there is little evidence that prophylaxis reduces risk of infection and two, in patients who have undiagnosed active MAC infection, the use of a single agent could contribute to the development of drug resistance. Patients who were previously initiated should have their prophylaxis discontinued. MAC prophylaxis should only be considered for patients who are unable to take a fully suppressive antiretroviral regimen.

References:MAC PPx in AIDS  
Cryoglobulins are proteins that precipitate below 37 degrees. In evaluating for the presence of cryoglobulins, proper collection and processing of blood is crucial to reduce the chances of a false negative result. The blood should be collected in a pre-warmed plain red-top tube and kept at 37 degrees until blood is fully clotted (about 1 hour), after which the sample can be stored and transported at room temperature. Clinicians can help improve the yield by collecting the sample and keeping it close to the body (for example, in the armpit) during transport to the lab, then ensuring that the lab keeps the sample incubated at the appropriate temperature until the full hour has elapsed. 

References:Lab Testing for Cryoglobulins