Hypoparathyroidism: update of guidelines from the 2022 International Task Force

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TL;DR

The 2022 International Task Force guidelines update the definition of chronic postsurgical hypoparathyroidism to persistence for at least 12 months after surgery. Key recommendations include using serum PTH >10 pg/mL 12-24 hours post-thyroidectomy to predict unlikely permanent disease, and conventional therapy with calcium and active vitamin D as first-line treatment. The guidelines emphasize monitoring for complications such as cataracts (24%), nephrolithiasis (15%), and renal insufficiency (13%), and suggest PTH replacement when conventional therapy is inadequate.

Full summary

3,200 CHARS

**Background** Hypoparathyroidism (HypoPT) is a rare disorder characterized by hypocalcemia due to insufficient parathyroid hormone (PTH). The 2022 International Task Force guidelines update the 2016 guidelines, incorporating new evidence from literature published between 2015 and 2020. The guidelines aim to provide evidence-based recommendations for prevention, diagnosis, and management of chronic HypoPT.

**Methods** Four HypoPT Task Forces included 50 international experts. A formal GRADE methodology was used for 7 recommendations, while 20 recommendations were based on narrative reviews. Systematic literature searches were conducted in PubMed, Medline, Embase, and Cochrane, covering publications from 1940 to 2020, with emphasis on 2015-2020. The process involved virtual meetings over 18 months due to the COVID-19 pandemic, with input from about 100 individuals during two virtual meetings. The document underwent a 6-8-week comment period by endorsing organizations.

**Key Results** - **Definition**: Chronic postsurgical HypoPT is now defined as persisting for at least 12 months after surgery (previously 6 months). - **Prediction**: Serum PTH <10 pg/mL (1.05 pmol/L) within 12-24 hours after total thyroidectomy predicts possible permanent HypoPT (strong recommendation, moderate quality evidence). PTH >10 pg/mL virtually excludes long-term disease. - **Complications**: Based on observational studies, the most common complications include cataracts (24%), infections (18%), nephrocalcinosis/nephrolithiasis (15%), renal insufficiency (13%), seizures (12%), depression (11%), ischemic heart disease (9%), and arrhythmias (7%). - **Monitoring**: For stable patients, serum calcium, phosphorus, magnesium, creatinine, and eGFR should be assessed every 3-12 months; 25OHD every 6-12 months; 24-hour urine calcium and creatinine every 6-24 months. Baseline renal imaging is recommended. - **Management**: Conventional therapy with calcium and active vitamin D is first-line (weak recommendation, low quality evidence). Target serum calcium is the lower half of the normal reference range. 24-hour urinary calcium should be <250 mg for women and <300 mg for men. PTH replacement is considered when conventional therapy is inadequate (e.g., symptomatic hypocalcemia, hyperphosphatemia, renal insufficiency, hypercalciuria, poor quality of life). - **Pregnancy**: Serum calcium should be maintained in the mid- to low-normal range, monitored every 3-4 weeks. Thiazide diuretics, high-dose vitamin D, and PTH analogues should be avoided.

**Clinical Implications** These guidelines provide updated, evidence-based recommendations for diagnosing, monitoring, and managing chronic HypoPT. The change in definition to 12 months for postsurgical HypoPT may reduce unnecessary long-term treatment in patients who might recover. The use of early PTH measurement helps identify patients unlikely to develop permanent disease. The emphasis on monitoring for complications and managing hypercalciuria aims to reduce renal and other end-organ damage. The guidelines also highlight the limited evidence for PTH replacement and the need for future research, particularly in pregnancy and lactation.