Methyltestosterone-induced night blindness.

A 59-year-old man presented with a 3-month history of night blindness and a 9-month history of steatorrhea. Both symptoms had appeared after he had begun taking methyltestosterone. Investigations revealed low serum levels of carotene (0.1 mmol/L) and vitamin A (0.4 to 0.7 mmol/L), anomalous colour perception, elevation of the rod threshold by 3.5 log units in dark adaptometry, and decreased b-wave amplitudes in photopic and scotopic electroretinograms. No biochemical evidence of cholestasis was elicited. The symptoms and the biochemical and electrophysiologic abnormalities resolved within 9 months of the discontinuation of methyltestosterone.