Occam’s razor: when evaluating multiple competing theories, the simpler explanation of an entity is to be preferred.
Solid logic, but not infallible.
This week I took care of a patient with a serum calcium of 17.5 mg/dL. Calciums that high are almost always malignant in nature. But we did the internal medicine thing and ran the algorithm. First branch point, “Is this PTH dependent or independent hypercalcemia?” The PTH came back at 220 pg/mL. Primary hyperparathyroidism. Case closed…or not.
A calcium of 17.5 mg/dL is extraordinarily high for primary hyperparathyroidism. In fact it would have been the highest calcium I had ever seen in primary hyperparathyroidism. I learned as a fellow, that whenever you think “this is the worst case of X I have ever seen, consider that maybe it is not the worst case of X but rather a more pedestrian case of Y.” Maybe, instead of the worst case of primary hyperparathyroidism this was two diseases instead of one.
Hickam’s dictum: Patients can have as many diseases as they damn well please.
The workup revealed a kappa/lambda ratio of 250 to 1. The patient didn’t just have primary hyperparathyroidism. They had primary hyperparathyroidism and multiple myeloma (or MGRS, the bone marrow biopsy is still pending).
The myeloma amplified the hyperparathyroidism beyond reason.
When you see the most dramatic presentation of a common codition, don’t just marvel at its severity, but ask yourself could this be somehting else entirely?
Sometimes Occam loses and Hickam wins.