Hypoparathyroidism - Q-Notes for Adult Medicine

clinical practice
Vitamin D metabolites†
Vitamin D 2 (ergocalciferol)
or vitamin D 3 (cholecalciferol)
1,25-dihydroxyvitamin D 3
(calcitriol)
25,000–100,000 IU once daily; time to onset of action, 10–14 days; time to
offset of action, 14–75 days
0.25–1.0 μg once or twice daily; time to onset of action, 1–2 days; time to
offset of action, 2–3 days
Vitamin D 3 is more potent than D 2 but
may be more difficult to obtain at the
doses needed. Because of the long
half-life of vitamin D 2 and D 3 , dosing
can be adjusted and serum levels of
calcium, albumin, phosphorus, and
creatinine determined every 4 weeks,
once symptoms have been controlled.
Most active metabolite of vitamin D at the
vitamin D receptor in vivo
Cooper and Gottoes, 46
Tohme and Bilezikian,
49 Brickman, 50
Rude, 51 Okano et
al., 52 Halabe et al. 53
1α-hydroxyvitamin D 3
(alfacalcidiol)
0.5–3.0 μg (occasionally up to 5.0 μg) daily; time to onset of action, 1–2
days; time to offset of action, 5–7 days
Dihydrotachysterol 0.2–1.0 mg once daily; time to onset of action, 4–7 days; time to offset of
action, 7–21 days
This metabolite is rapidly converted to
1,25-dihydroxyvitamin D 3 in vivo; its
duration of action closely resembles
that of 1,25-dihydroxyvitamin D 3
Thiazide diuretics Added to prevent or control hypercalciuria;
should be combined with a low-salt
diet (80–100 mmol of sodium per day)
to promote calcium retention; doses
are increased as tolerated; adverse
events include hypokalemia and hyponatremia
Hydrochlorothiazide 25–100 mg per day Doses at high end of these ranges are usually
needed to achieve substantial lowering
of urinary calcium
Chlorthalidone 25–100 mg per day
Porter et al. 54
Amiloride and hydrochlorothiazide
(Moduretic)
50 mg of hydrochlorothiazide combined with 5 mg of amiloride once daily Potassium-sparing diuretics may be used to
prevent hypokalemia
* The list of calcium preparations is not comprehensive. Of the calcium preparations available, only the carbonate and citrate salts contain sufficient elemental calcium (per tablet) for
the efficient treatment of most patients with hypoparathyroidism. Other preparations may be used in patients who cannot tolerate citrate and carbonate salts. The percentage of elemental
calcium is lower in these other preparations: calcium lactate (13%), calcium gluconate (9%), and calcium glubionate (6.6%); thus, larger numbers of tablets must be given.
† Vitamin D toxicity is an important concern and may occur at any time. Manifestations may include altered mental status, fatigue, thirst, dehydration, reduced renal function, nephrolithiasis,
and constipation. Treatment involves discontinuation of the vitamin D preparation and the calcium salt. Depending on the severity, and especially if the toxic effects are from
vitamin D metabolites with long half-lives, intravenous saline hydration and possibly oral glucocorticoids may be warranted to antagonize vitamin D action and more rapidly restore
normocalcemia. Levels of 25-hydroxyvitamin D should be monitored, even in patients receiving calcitrol and alfacalcidiol to prevent vitamin D insufficiency. The target 25-hydroxyvitamin
D level is 30 ng/ml or more.
n engl j med 359;4 www.nejm.org july 24, 2008 399
Downloaded from www.nejm.org at KAISER PERMANENTE on July 23, 2008 .
Copyright © 2008 Massachusetts Medical Society. All rights reserved.