Calcium, parathyroid hormone, and vitamin D in patients with primary hyperparathyroidism: normograms developed from 10,000 cases.
OBJECTIVE
To better define the typical and atypical biochemical profiles of patients with surgically proven primary hyperparathyroidism.


METHODS
In this single-center, prospectively conducted study of consecutive patients with surgically proven primary hyperparathyroidism over a 7-year period, we analyzed serum calcium, parathyroid hormone, and 25-hydroxyvitamin D concentrations.


RESULTS
A total of 10 000 patients were included, and more than 210 000 calcium, parathyroid hormone, and 25-hydroxyvitamin D values were evaluated. Both calcium and parathyroid hormone levels demonstrated a Gaussian distribution with the average calcium concentration being 10.9 ± 0.6 mg/dL and the average parathyroid hormone concentration being 105.8 ± 48 pg/mL. The average highest calcium and parathyroid hormone concentrations were 11.4 ± 0.7 mg/dL and 115.3 ± 50 pg/mL, respectively. At least 1 calcium value of 11.0 mg/dL was seen in 87% of patients, but only 21% had 1 or more calcium value above 11.5 mg/dL. Only 7% had a single serum calcium level reaching 12.0 mg/dL. Normocalcemic hyperparathyroidism was seen in just under 3% of patients who had identical findings at surgery. An average parathyroid hormone concentration less than 65 pg/mL was seen in 16%, with 10% of patients who had no high parathyroid hormone values. The average 25-hydroxyvitamin D concentration was 22.4 ± 9 ng/mL, with levels decreasing as calcium levels increased (P<.001); 36% had 25-hydroxyvitamin D levels below 20 ng/mL.


CONCLUSIONS
Patients with PHPT present with a number of distinct biochemical profiles, but as a group, they present with a near-normal Gaussian distribution of both calcium and parathyroid hormone levels. Either serum calcium or parathyroid hormone remained normal in 13% of patients, yet the findings at surgery are similar to those of patients with elevated calcium or parathyroid hormone. Low 25-hydroxyvitamin D is an expected finding in patients with PHPT, decreasing as serum calcium levels increase.
Norman Parathyroid Center, Tampa, FL, USA. jnorman@parathyroid.com
James
J
Norman
Arnold
A
Goodman
Douglas
D
Politz
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000097:blood*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000097:blood*; D008297:Male; D008875:Middle Aged; D049451:Nomograms; D010281:Parathyroid Hormone / Q000097:blood*; D014807:Vitamin D / Q000097:blood*; D055815:Young Adult
D010281:Parathyroid Hormone; D014807:Vitamin D; D002118:Calcium