Unexpected serum parathyroid hormone profiles in some patients with primary hyperparathyroidism.
BACKGROUND
Third-generation parathyroid hormone (PTH) assays have been reported to measure only intact PTH(1-84), in contrast to second-generation assays, which also detect PTH(7-84) fragments. Higher PTH measurements were observed with third- than with second-generation PTH assays in a few patients with either severe primary hyperparathyroidism or parathyroid carcinoma.


METHODS
We analyzed biological data [second- and third-generation PTH assays, 25-hydroxyvitamin D (25-OHD), calcium, and phosphate concentrations] obtained before and after surgery for 2 groups of patients selected from a large series of consecutive patients with primary hyperparathyroidism (PHPT): 7 female patients with surgically and histologically confirmed PHPT (group 1) and a matched group (group 2).


RESULTS
For group 1 but not group 2, PTH concentrations measured by third-generation PTH assays before surgery were higher than those measured by the second-generation assays. Circulating 25-OHD, calcium, and phosphate concentrations were similar in both groups. In addition, PTH values measured with the third-generation PTH assays in group 1 decreased after surgery.


CONCLUSIONS
Our results confirm that third-generation PTH assays do not measure only PTH(1-84). The frequency of this unexpected finding of markedly lower PTH concentrations than previously reported was approximately 5% in patients with PHPT without malignancy. We do not know whether the presence of this unexpected profile is predictive of malignancy.
Department of Hormonal Biology, Hôpital Saint-Louis, Paris, France. philippe.boudou@sls.aphp.fr
Philippe
P
Boudou
Fidaa
F
Ibrahim
Catherine
C
Cormier
Emile
E
Sarfati
Jean-Claude
JC
Souberbielle
D000328:Adult; D000368:Aged; D002118:Calcium / Q000097:blood; D005260:Female; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood; D049950:Hyperparathyroidism, Primary / Q000097:blood* / Q000601:surgery; D007118:Immunoassay; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D010710:Phosphates / Q000097:blood
D006887:Hydroxycholecalciferols; D010281:Parathyroid Hormone; D010710:Phosphates; D002118:Calcium