hypoparathyroidism
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Etiology
- inadvertant surgical removal of parathyroid glands during surgical thyroidectomy*
- parathyroidectomy* for hyperparathyroidism
- post-irradiation of the neck
- autoimmune disease - NALP5 autoantibodies
- congenital disorders, genetic disorders
- infiltrative diseases
- Mg+2 deficiency diminishes PTH release & effect
- DiGeorge syndrome
* removal of all 4 parathyroids or impairment of their blood supply is required for permanent hypoparathyroidism; otherwise hypoparathyroidism & hypocalcemia is transient of duration days to weeks
Clinical manifestations
- signs & symptoms of hypocalcemia
- mostly paresthesias, muscle cramps
- most prominent in patients with rapid drop in serum calcium after surgery
- tetany, seizures & prolonged QTc[9]
Laboratory
- serum calcium & serum magnesium[2]
- ionized calcium
- 24 hour urine calcium & calcium/creatinine in urine (assess hypercalciuria)
- intact parathyroid hormone (fasting)
- serum phosphate may be elevated (target < 6.5 mg/dL)[2]
- NALP5 autoantibody in serum (no Loinc)
Diagnostic procedures
- electrocardiogram
- prolonged QT interval with more severe hypocalcemia
- routine renal ultrasound of low yield in asymptomatic patients (5%)[8]
- detect asymptomatic nephrolithiasis or nephrocalcinosis
Radiology
- bone-mineral density testing
- evaluate indication for parathyroidectomy
- risk factors similar to general population in asymptomatic patients[8]
Management
- supplemental calcium
- oral calcium will increase serum calcium within minutes in patients with inadvertant surgical removal of parathyroid glands during surgical thyroidectomy[2][3]
- 1-2 g of elemental calcium PO TID (initially)
- 0.5-1 g PO TID with meals (maintenance)
- goals are to maintain serum Ca+2 in low-normal range, 8.0-8.5 mg/dL & avoid hypercalciuria, urinary calcium to < 300 mg/24 hours[2]
- decrease or increase oral calcium to meet these goals
- IV calcium (CaCl) may be indicated in patients with tetany or QT prolongation[2][3]
- serum magnesium must be corrected to 2.0 mg/dL or higher to correct hypercalcemia[2]
- vitamin D or 1,25-dihydroxyvitamin D3 (calcitriol)
- calcitriol (preferred agent)
- Vitamin D
- if hypercalcemia develops, stop vitamin D, then restart at a lower dose
- calcium acetate (Phoslo) as needed to maintain serum phosphorus < 6.5 mg/dL
- hydrochlorothiazide 50 mg PO QD to reduce calciuria
- important NOT to fully normalize serum calcium because of risk of nephrolithiasis (absence of PTH renal effect)[2]
- teriparatide not FDA-approved for use in hypoparathyroidism
- safety & effectiveness not established[2]
More general terms
More specific terms
- autosomal dominant hypoparathyroidism; familial isolated hypoparathyroidism; autosomal dominant hypocalcemia
- DiGeorge syndrome; velocardiofacial syndrome; pharyngeal pouch syndrome
- hypoparathyroidism, sensorineural deafness & renal dysplasia (HDR syndrome)
Additional terms
References
- ↑ Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 472, 495-496
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 Medical Knowledge Self Assessment Program (MKSAP) 11, 15, 16, 17, 18. American College of Physicians, Philadelphia 1998, 2009, 2012, 2015, 2018.
- ↑ 3.0 3.1 3.2 3.3 Khan MI, Waguespack SG, Hu MI. Medical management of postsurgical hypoparathyroidism. Endocr Pract. 2011 Mar-Apr;17 Suppl 1:18-25 PMID: https://www.ncbi.nlm.nih.gov/pubmed/21134871
- ↑ Shoback D Clinical practice. Hypoparathyroidism. N Engl J Med. 2008 Jul 24;359(4):391-403 PMID: https://www.ncbi.nlm.nih.gov/pubmed/18650515
- ↑ Al-Azem H, Khan AA. Hypoparathyroidism. Best Pract Res Clin Endocrinol Metab. 2012 Aug;26(4):517-22. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/22863393
- ↑ Brandi ML, Bilezikian JP, Shoback D et al Management of Hypoparathyroidism: Summary Statement and Guidelines. J Clin Endocrinol Metab. 2016 Jun;101(6):2273-83. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/26943719
- ↑ Gafni RI, Collins MT Hypoparathyroidism. N Engl J Med 2019; 380:1738-1747. May 2, 2019 PMID: https://www.ncbi.nlm.nih.gov/pubmed/31042826 https://www.nejm.org/doi/full/10.1056/NEJMcp1800213
- ↑ 8.0 8.1 8.2 Reid LJ, Muthukrishnan B, Patel D, Seckl JR, Gibb FW. Predictors of nephrolithiasis, osteoporosis, and mortality in primary hyperparathyroidism. J Clin Endocrinol Metab 2019 Sep 1; 104:3692-3700 PMID: https://www.ncbi.nlm.nih.gov/pubmed/30916764 https://academic.oup.com/jcem/article-abstract/104/9/3692/5419224?redirectedFrom=fulltext
- ↑ 9.0 9.1 NEJM Knowledge+ Endocrinology
Patient information
hypoparathyroidism patient information