A case of active acromegaly with reduced height and type 1 renal tubular acidosis

A 41-year-old man with acromegaly was suffering from chronic, progressive backache and aware of reduction in his body height. Endocrine studies revealed increased glucose non-suppressible serum growth hormone (GH) and serum prolactin (PRL). Pituitary microadenoma was detected by a computerized axial tomogram and subsequently resected by trans-sphenoidal adenomectomy. The tumor proved to be a mixed GH- and PRL-secreting adenoma by electron microscopy and immunoperoxidase staining. Concurrent investigation of backache and reduced height disclosed markedly reduced radiodensity of the spinal bones, bilateral nephrocalcinosis, and hypercalciuria, which were ascribed to renal tubular acidosis (RTA) demonstrated by reduced urinary excretion of acids and insufficient reduction of urinary pH following oral administration of ammonium chloride. From the analogy to certain endocrinopathies, it appears likely that enhanced calcium metabolism and resultant hypercalciuria due to excess GH and PRL have led to the development of RTA, which further enhanced calciuria. Such enhanced calcium metabolism and consequent hypercalicuria conceivably led to accelerated demineralization of the spine and resulted in the reduced height of this patient in his early forties.