Calcium, Parathyroid Hormone, and Vitamin D in Patients with Primary Hyperparathyroidism: Normograms Developed from 10 000 Cases

James Norman, Arnold Goodman, Douglas Politz
2011 Endocrine Practice  
Objective: To define more clearly the typical and atypical biochemical profiles of patients with surgically proven primary hyperparathyroidism. Methods: A single-center, prospectively conducted study of serum calcium, parathyroid hormone, and Vitamin D in 10,000 consecutive patients over a 7 year period with surgically proven PHPT. Over 210,000 calcium, PTH, and vitamin D values were evaluated. Results: Both calcium and PTH levels demonstrate a Gaussian distribution with the average calcium
more » ... g 10.9+0.6 mg/dl and the average PTH being 105.8+48 pg/ml. The average highest calcium and PTH was 11.4+0.7 mg/dl and 115.3+50 pg/ml, respectively. At least one calcium level of 11.0 mg/dl is seen in 87% of patients, but only 21% had one or more calcium levels above 11.5 mg/dl. Only 7% had a single serum calcium level reaching 12.0 mg/dl. Normocalcemic HPT was seen in 2.5% of patients who had identical findings at surgery. An average PTH less than 65 pg/ml was seen in 16.5% with 10.5% having zero high PTH values. The average vitamin D-25 was 22.4+9 ng/ml, with levels decreasing as calcium levels increased (p<0.001); 36% had vitamin D-25 levels below 20ng/ml. Conclusion: Patients with PHPT present with a number of distinct biochemical profiles, but as a group present with a near-normal Gaussian distribution of both calcium and PTH. Either serum calcium or PTH remained normal in 13% of patients yet the findings at surgery are similar to those with elevated calcium or PTH. Low vitamin D is an expected finding in patients with PHPT, decreasing as serum calcium levels increased.
doi:10.4158/ep09346.or pmid:21134884 fatcat:gjvz5ui7kvcxdd65h3xahlgy7y