Primary hypoparathyroidism is a condition characterized by hypocalcemia and hyperphosphatemia resulting from the primary absence or deficiency of parathyroid hormone (PTH) or from the secretion of biologically inactive PTH.
Diagnosis of Primary Hypoparathyroidism
- Blood tests: Hypocalcemia, hyperphosphatemia, low or undetectable serum PTH levels, low 1,25-dihydroxycholecalciferol (1,25(OH)2D3) levels.
- Urine tests: An increase in urinary phosphate and cyclic adenosine monophosphate excretion after the administration of exogenous PTH.
- Electrocardiography (ECG): Features of hypocalcemia (intermittent QT prolongation, or intermittent prolongation of the QTc (corrected QT interval) secondary to a lengthened ST segment).
- Imaging studies may reveal calcifications in the basal ganglia and in soft tissues as well as increased bone mineral density (osteosclerosis).
- Nerve conduction tests and electromyography (EMG): Decreased nerve excitability and chronaxie, spontaneous high-frequency biphasic action potentials in skeletal muscles.
Diagnosis and Evaluation of Hypoparathyroidism
- Hypocalcemia (albumin-adjusted) confirmed on at least two occasions separated by at least 2 weeks.
- PTH concentration, by second- or third-generation immunoassay, that is undetectable or inappropriately low (ie, <20 pg/mL) in the presence of hypocalcemia on at least two occasions.
- Phosphate levels in the upper normal or frankly elevated range (helpful but not mandatory).
- After neck surgery, chronic hypoparathyroidism is established only after 6 months
Indications for Considering the Use of rhPTH (1-84) in Hypoparathyroidism
- Inadequate control of the serum calcium concentration (this could be due to intercurrent illness, compliance, absorption, or intrinsic changes in requirements that are beyond facile correction with calcium and active vitamin D)
- Oral calcium/vitamin D medications required to control the serum calcium or symptoms that exceed 2.5 g of calcium or >1.5 µg of active vitamin D or >3.0 µg of the 1-∝ vitamin D analog
- Hypercalciuria, renal stones, nephrocalcinosis, stone risk, or reduced creatinine clearance or estimated Glomerular Filtration Rate (GFR <60 mL/min)
- Hyperphosphatemia and/or calcium-phosphate product that exceeds 55 mg²/dL² (4.4 mmol² /L²)
- A gastrointestinal tract disorder that is associated with malabsorption
- Reduced quality of life
- Clarke BL, Brown EM, Collins MT, Jüppner H, Lakatos P, Levine MA, Mannstadt MM, Bilezikian JP, Romanischen AF, Thakker RV. Epidemiology and Diagnosis of Hypoparathyroidism. J Clin Endocrinol Metab. 2016 Jun;101(6):2284-99. [Medline]
- Brandi ML, Bilezikian JP, Shoback D, Bouillon R, Clarke BL, Thakker RV, Khan AA, Potts JT Jr. Management of Hypoparathyroidism: Summary Statement and Guidelines. J Clin Endocrinol Metab. 2016 Jun;101(6):2273-83. [Medline]
Created May 09, 2019.