Effect of calcium administration on renal responsiveness to parathyroid hormone in pseudohypoparathyroidism type I and II -- in comparison with normals, idiopathic and surgical hypoparathyroidism.
A 31-year-old man and a 12-year-old girl were diagnosed as pseudohypoparathyroidism (PHP) Type I because of a failure to respond to the administration of parathyroid hormone (PTH) with increased urinary excretion of phosphate and cyclic adenosine-3', 5'-monophosphate (cAMP). A 22-year-old woman was diagnosed as PHP Type II because there was no increase in the urinary excretion of phosphate despite of a marked increase in urinary cAMP excretion. With the combined calcium-PTH infusion or PTH infusion after vitamin D therapy, renal response was improved in these patients. Also dibutyryl adenosine-3'-5'-cyclic monophosphate (dbcAMP) infusion evoked an increased urinary phosphate excretion in all of the patients. The metabolic defect of our patients with PHP Type I may be caused not by a lack or defective form of PTH-sensitive receptor adenylate cyclase complex but rather by an abnormal conformation in the plasma membrane-associated receptor adenylate cyclase enzyme complex in kidney. In the patient with PHP Type II, as cAMP generation is intact, the metabolic defect might be related to a defect of calcium mobilization in renal tubular cells in response to PTH.
D000328:Adult; D003994:Bucladesine; D002118:Calcium / Q000008:administration & dosage; D002648:Child; D000242:Cyclic AMP / Q000652:urine; D005260:Female; D006801:Humans; D007011:Hypoparathyroidism / Q000378:metabolism*; D007668:Kidney / Q000187:drug effects*; D008274:Magnesium / Q000652:urine; D008297:Male; D010281:Parathyroid Hormone; D010710:Phosphates / Q000652:urine; D011547:Pseudohypoparathyroidism / Q000378:metabolism*
D010281:Parathyroid Hormone; D010710:Phosphates; D003994:Bucladesine; D000242:Cyclic AMP; D008274:Magnesium; D002118:Calcium