In pseudohypoparathyroidism (PHP) the findings of hypocalcemia and hyperphosphatemia are not the result of a deficiency of parathormone (PTH) but of a tissue insensitivity to this hormone. There appears to be sufficient PTH available to bone and kidney in this syndrome, and PTH is released in a normal fashion after appropriate stimuli.1,2
The unresponsiveness of PTH resides in the renal cortical tubular tissue where the hormone fails to activate adenyl cyclase with a resulting defective renal excretion of cyclic 3′,5′-adenosine monophosphate (AMP) (second messenger).3 Two cases of PHP are presented which confirm the failure of urinary cyclic 3′,5′-AMP levels to rise following PTH infusion. Since the many somatic and growth abnormalities in PHP cannot be explained by PTH insensitivity alone, an evaluation of other endocrine functions was undertaken.
—An 11-year-old white girl was admitted to Abington Memorial Hospital because of increasing involuntary movements, calcification of the basal ganglia
Greenberg SR, Karabell S, Saade GA. Pseudohypoparathyroidism: A Disease of the Second Messenger (3',5'-Cyclic AMP). Arch Intern Med. 1972;129(4):633–637. doi:10.1001/archinte.1972.00320040109014
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