Development and treatment of tertiary hyperparathyroidism in patients with pseudohypoparathyroidism type 1B.
BACKGROUND
Pseudohypoparathyroidism type 1B (PHP1B) patients have PTH resistance at the renal proximal tubule and develop hypocalcemia and secondary hyperparathyroidism. Hyperparathyroid bone disease also develops in some patients. PHP1B patients are at theoretical risk of developing tertiary hyperparathyroidism.


METHODS
Patients were studied in a clinical research center.


METHODS
Five female PHP1B patients presented with hypercalcemia and elevated PTH.


METHODS
Patients either underwent parathyroidectomy (n = 4) or received cinacalcet (n = 1).


METHODS
Serum calcium and PTH were serially measured before and after intervention.


RESULTS
Five PHP1B patients developed concomitantly elevated serum calcium and PTH levels (range, 235-864 ng/liter) requiring termination of calcium and vitamin D therapy (time after diagnosis, 21-42 yr; median, 34 yr), consistent with tertiary hyperparathyroidism. Four patients underwent parathyroidectomy with removal of one (n = 2) or two (n = 2) enlarged parathyroid glands. Calcium and vitamin D therapy was reinstituted postoperatively, and at 93-month median follow-up, PTH levels ranged between 56 and 182 (normal, <87) ng/liter. One patient was treated with cinacalcet, resulting in resolution of hypercalcemia.


CONCLUSIONS
PHP1B patients are at risk of developing tertiary hyperparathyroidism and/or hyperparathyroid bone disease and should therefore be treated with sufficient doses of calcium and vitamin D to achieve serum calcium and PTH levels within or as close to the normal range as possible. Surgery is the treatment of choice in this setting. Cinacalcet may be a useful alternative in those who do not undergo surgery.
Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-1752, USA.
Nicola M
NM
Neary
Diala
D
El-Maouche
Rachel
R
Hopkins
Steven K
SK
Libutti
Arnold M
AM
Moses
Lee S
LS
Weinstein
D000293:Adolescent; D017668:Age of Onset; D002117:Calcitriol / Q000627:therapeutic use; D002118:Calcium / Q000627:therapeutic use; D002675:Child, Preschool; D018450:Disease Progression; D004872:Ergocalciferols / Q000627:therapeutic use; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000150:complications* / Q000235:genetics; D006996:Hypocalcemia / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000209:etiology; D010002:Osteitis Fibrosa Cystica / Q000209:etiology; D010280:Parathyroid Glands / Q000601:surgery; D010281:Parathyroid Hormone / Q000097:blood; D016105:Parathyroidectomy; D011547:Pseudohypoparathyroidism / Q000209:etiology* / Q000235:genetics; D012640:Seizures / Q000209:etiology; D051438:Syntaxin 16 / Q000235:genetics; D055815:Young Adult
D004872:Ergocalciferols; D010281:Parathyroid Hormone; C496118:STX16 protein, human; D051438:Syntaxin 16; D002117:Calcitriol; D002118:Calcium