A 6-hour human parathyroid hormone (1-34) infusion protocol: studies in normal and hypoparathyroid subjects.
Parathyroid hormone (PTH)-resistant states are usually diagnosed by the failure of an acute PTH injection to elicit a rise in urinary cAMP and phosphate or, less commonly, by the failure of repeated PTH injections to raise serum calcium. We have established a 6 hour infusion of human PTH (1-34) which identifies PTH-resistant hypoparathyroid subjects on the basis of serum 1,25-dihydroxyvitamin D (1,25(OH)2D) and calcium responses. 1,25-Dihydroxyvitamin D levels increased by at least 58 pmol/liter and serum calcium by at least 0.1 mmol/liter in PTH-responsive hypoparathyroid subjects (n = 6), whereas in pseudohypoparathyroid subjects (n = 5) these levels rose by less than 22 pmol/liter and 0.06 mmol/liter respectively. The responsiveness of urinary phosphate excretion, expressed as the renal threshold phosphate concentration (TmPO4/GFR), to PTH also clearly separated the pseudohypoparathyroid patients from the other subjects. Differences in urinary calcium responses were observed though this parameter was less reliable in the identification of individual PTH-resistant or PTH-sensitive hypoparathyroid patients. Nephrogenous cAMP did not discriminate between groups when this protocol was used. This test has the potential to facilitate and extend the classification of PTH-resistant states.
McElduff
A
A
Department of Endocrinology, Royal North Shore Hospital, St. Leonards, N.S.W., Australia.
Lissner
D
D
Wilkinson
M
M
Cornish
C
C
Posen
S
S
D000328:Adult; D000368:Aged; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000097:blood / Q000652:urine; D000242:Cyclic AMP / Q000652:urine; D005260:Female; D006801:Humans; D007011:Hypoparathyroidism / Q000097:blood* / Q000652:urine; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D010710:Phosphates / Q000652:urine; D011547:Pseudohypoparathyroidism / Q000097:blood* / Q000652:urine; D012016:Reference Values; D019379:Teriparatide
D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010710:Phosphates; D019379:Teriparatide; D000242:Cyclic AMP; D002117:Calcitriol; D002118:Calcium