Wednesday, November 23, 2016

Management Chronic Hypocalcemia Secondary Hypothyrodism

Goal of Therapy
  • The goals of therapy in patients with hypoparathyroidism are to relieve symptoms, to raise and maintain the serum calcium concentration in the low-normal range, eg, 8.0 to 8.5 mg/dL (2.0 to 2.1 mmol/l), and to prevent iatrogenic development of kidney stones.
  • Attainment of higher serum calcium values is not necessary and is usually limited by the development of hypercalciuria due to the loss of renal calcium-retaining effects of PTH.

Uptodate
American College of Endocrinology , 2015
Calcium
  • Intravenous calcium is indicated to prevent acute hypocalcemia in patients with chronic hypoparathyroidism who become unable to take or absorb oral supplements.
  • For adults with stable chronic hypoparathyroidism, the dose of oral calcium is typically 1 to 2 g of elemental calcium daily, in divided doses
  • Although calcium carbonate is often used (it is the least expensive), it may be less well-absorbed in older patients and those who have achlorhydria
Vitamin D Analogue


  • Several preparations of vitamin D and the various preparations differ in onset of action, duration of action, and cost. Because PTH is required for the renal conversion of calcidiol (25-hydroxyvitamin D [25{OH}D]) to the active metabolite calcitriol (1,25-dihydroxyvitamin D [1,25D]), calcitriol is often regarded as the treatment of choice .
  • The advantages of calcitriol include lack of necessity for endogenous activation, rapid onset of action (hours), and a biologic half-life of about four to six hours.
Thiazide


  • Some patients will require the addition of thiazide diuretics (12.5 to 50 mg daily), with or without dietary sodium restriction, to decrease urinary calcium excretion 
Second-line therapy 
In view of the fact that hypoparathyroidism is a hormonal deficiency, replacement of the missing hormone, ie, PTH 1-84, is a potentially attractive intervention.
For patients with chronic hypoparathyroidism who cannot maintain stable serum and urinary calcium levels with calcium and vitamin D supplementation, the addition of recombinant PTH 1-84 is an option

Calcium
  • Calcium is typically provided as calcium carbonate or calcium citrate.
  • Doses ranging up to 9,450 mg per day have been reported, with most patients requiring 1,500 mg elemental calcium daily.
  • Dosing is divided into 2 or 3 split doses to maximize absorption.
Vitamin D Analogue


  • Calcitriol improves intestinal calcium absorption and is almost always required. Doses range from 0.125 to 4.0 mcg/day, with most patients requiring 0.25 mcg daily.
  • The doses are typically divided when 1 mcg or more per day is required.
  • Vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol) are occasionally used along with the activated metabolite of vitamin D (calcitriol) and may help to provide smoother control of calcium levels.
Thiazide


  • Thiazide diuretics can be added to the regimen when calcium control is difficult or hypercalcuria (>150 mg/24 h) is a problem.
  • Thiazide diuretics enhance distal renal tubular calcium reabsorption, thereby increasing serum calcium and reducing urinary calcium excretion.
  • Hydrochlorothiazide (12.5–50 mg daily) can be effective.


A new option for the treatment of hypoparathyroidism recently approved by the U.S. Food and Drug Administration in January 2015, is recombinant human PTH (1-84), which is identical in structure to the fulllength endogenous hormone.







Reference : 


  1. Diagnosis and management of hypocalcaemia https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2413335/
  2.  AACE/ACE Post Operative Hypoparathyrodism – Definitions & Management http://journals.aace.com/doi/full/10.4158/ep14462.dsc










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