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08/22/2011 - hypothyroidism and carotenemia

posted Sep 28, 2011, 5:19 PM by Chief Resident   [ updated Sep 28, 2011, 5:20 PM by Purnema Madahar ]

In intake, Natalie Zelta presented a fascinating case of a 'yellow patient'. It taught me that not every yellow patient is jaundiced: don't forget hypercarotenemia, as Rohit Das pointed out later in the day. Anyone who thinks that's quite a jump is correct, and you would really need to know the details of the case or check out the attached case report.

The case brought up the question how sensitive the typical signs we associate with hypothyroidism are. Not very sensitive, as it turns out. In a very nicely executed study that looked at this question in a prospective, cross-sectional manner, the negative likelihood ratios for coarse skin, slow movements, bradycardia, pretibial edema, puffy face or delayed ankle reflexes ranged from 1 (slow movement) to 0.42 (puffy face). The gold standard were TFTs. Although the attached paper does a great job of pointing out the pitfalls of this kind of study and of diagnostic studies in general, it might not even be fully applicable to our patient: only patients that answered in the affirmative when asked if they felt less energetic, lacked interest, had dry skin, gained weight or had a huskier voice were included. Also, patients with anemia were excluded.

Bottom line: the above signs are likely not sensitive enought to rule out hypothyroidism without lab tests, but it's a challenge to find a study that exactly fits our patient, a common problem when looking at diagnostic studies.

P.S.: for Rohit and Mary, some more 1952 goodness on carotenemia of hypothyroidism attached.