Calcium Supplements / Hypocalcemia

Calcium Supplements / Hypocalcemia

Reference Intake etc TUMS
Calcium Equivalents etc Hypocalcemia
Other reference tables  



Calcium  top of page icon

Dosing (Adults):
Hypocalcemia (dose depends on clinical condition and serum calcium level): Dose expressed in mg of elemental calcium: 1-2 grams or more/day in 2-4 divided doses. Antacid: Dosage based on acid-neutralizing capacity of specific product - generally, 1-2 tablets or 5-10 ml every 2 hours. Maximum: 7000 mg calcium carbonate per 24 hours.

Calcium / Vitamin D combinations:
Caltrate 600 + D (Vitamin D 200 IU + Calcium Carbonate 600mg): one tablet twice daily with food. Os-Cal 500 + D (Vitamin D 200 IU + Calcium Carbonate 500mg): Directions: One tablet two to three times a day with meals.

Dietary Reference Intake: (Dosage is in terms of elemental calcium):
19-50 years: 1000 mg/day. (e.g. 1.25 g CaCO3 bid) or (625 mg qid etc).
>51 years: 1200 mg/day.

Dosage form Elemental Ca++
Calcium Carbonate 500 mg chewable tabs ( Tums®)  200 mg
Calcium Carbonate 650 mg tablets  260 mg
Calcium Carbonate 1250 mg tablets OsCal 500®  500 mg
Calcium Carb 250 mg + Vit D 125 IU/tablet OsCal 250 +D® 100 mg
Calcium Glubionate syrup 1.8 gm/5ml NeoCalglucon® 115 mg/5ml

Calcium acetate (Phos Lo®) is available for phosphate binding and not calcium replacement in patients with renal insufficiency since its calcium absorption is poor.

 USUAL DOSE: 500 to 2000 mg elemental calcium a day, in divided doses (bid-qid). *Absorption is variable and depends on PTH, Vitamin D, and gastric pH.

Tums  top of page icon

Tums, Calcium Carbonate 500 mg
Tums E-X, Calcium Carbonate 750 mg
Tums ULTRA, Calcium Carbonate 1000 mg

Tums: Do not take more than 15 tablets in a 24-hour period or use the maximum dosage of this product for more than 2 weeks, except under the advice and supervision of a physician. If symptoms persist for 2 weeks, stop using this product and see a physician. Keep this and all drugs out of the reach of children.
Tums E-X: Do not take more than 10 tablets in a 24-hour period or use the maximum dosage of this product for more than two weeks, except under the advice and supervision of a physician. If symptoms persist for two weeks, stop using this product and see a physician. Keep this and all drugs out of the reach of children.
Tums ULTRA: Do not take more than 7 tablets in 24-hour period or use the maximum dosage of this product for more than two weeks, except under the advice and supervision of a physician. If symptoms persist for two weeks, stop using and see a physician. Keep this and all drugs out of the reach of children.

Dosage and Administration:
Tums: Chew 2-4 tablets as symptoms occur. Repeat hourly if symptoms return, or as directed by physician. Tums E-X: Chew 2-4 tablets as symptoms occur. Repeat hourly if symptoms return, or as directed by a physician. Tums ULTRA: Chew 2-3 tablets as symptoms occur. Repeat hourly if symptoms return, or as directed by a physician.

DIRECTIONS: Chew 2 tablets twice daily.
Supplement Facts
Serving Size Tums
2 Tablets
Tums E-X
2 Tablets
Tums E-X
Sugar Free
2 Tablets
Tums Ultra
2 Tablets
                   Amount Per Serving
5 10 5 10
Sorbitol (g)
-- -- 1 --
Sugars (g)
1 2 -- 3
Calcium (mg)
400 600 600 800
   % Daily Value
40 60 60 80
Sodium (mg)
-- 5 -- 10
   % Daily Value
-- <1% --

Calcium Reference Tables  top of page icon

Calcium salt
% Calcium

Calcium acetate 25.3 % 253 mg 12.2 meq
Calcium carbonate 40 % 400 20
Calcium chloride 27.2 272 13.6
Calcium citrate 21.1 211 10.5
Calcium glubionate 6.5 65 3.2
Calcium gluceptate 8.2 82 4.1
Calcium gluconate 9.3 93 4.65
Calcium lactate 13 130 6.5
Calcium phosphate, dibasic 23 230 11.5
Calcium phosphate, tribasic 38 380 19
Since the molecular weight of calcium is 40 and the valence is +2, 1 mg/dL is equivalent to 0.25 mmol/L and to 0.5 meq/L. Thus, the normal range of total plasma calcium concentration of 8.8 to 10.3 mg/dL is equivalent to 2.2 to 2.6 mmol/L and 4.4 to 5.2 meq/L.

PLASMA CALCIUM CONCENTRATION — The total plasma calcium concentration consists of three fractions:   1) Approximately 15 percent is bound to multiple organic and inorganic anions such as sulfate, phosphate, lactate, and citrate.  2) About 40 percent is bound to albumin in a ratio of 0.8 mg/dL (0.2 mmol/L or 0.4 meq/L) of calcium per 1.0 g/dL (10 g/L) of albumin.    3) The remaining 45 percent circulates as physiologically active ionized (or free) calcium. 

The ionized calcium concentration is tightly regulated by parathyroid hormone and vitamin D. The wide range in the normal total plasma calcium concentration is probably due to variations in the plasma concentration of albumin among normal healthy individuals and to variations in the state of hydration that can alter the albumin concentration.

Amount of
salt in
tablet (in
% elemental 
# of tabs to
provide 1g of Ca++
Calcium carbonate


625 40% 4
650 4
750 4
1250 2
1500 2
950 21.1% 5
Calcium gluconate


500 9.3% 22
650 17
1000 11
Calcium lactate 325 13% 24
650 12

REFERENCE RANGE:  Serum calcium: 8.4-10.2 mg/dL.
Corrected total calcium = total serum calcium + 0.8 (4.0 - measured serum albumin).

Hypocalcemia   top of page icon

Signs: paresthesias, tetany (especially carpopedal spasm), lethargy, confusion, seizures, Trousseau’s sign (carpal spasm occurring after the occlusion of the brachial artery with a blood pressure cuff for 3 minutes), Chvostek’s sign (contraction of the facial muscle in response to tapping the facial nerve anterior to the ear), QT prolongation.

Normal values: Total Calcium: 8.4-10.2 mg/dl (2.1-2.6 mmol/L). Ionized Calcium: 3.8-5.3 mg/dl (0.95-1.35 mmol/L). Protein binding: Moderate, approximately 45% in plasma.

1. Correct for hypoalbuminemia: If albumin is < 2, check ionized Ca++. Note that alkalosis augments Ca++ binding to albumin, decreasing the amount of ionized (effective) Ca++ and increasing severity of symptoms at a given level.
2. Determine Ca x PO4 product in mg/dl before administering calcium. If product is greater than 60 mg/dl, there is an increased risk of calcium phosphate precipitation in the cornea, lung, kidney, cardiac conduction system, and blood vessels.
3. Other: a) Correct hypomagnesemia. Determine potassium, phosphorus and magnesium levels. If the magnesium concentration is low, it should be corrected, otherwise it will be difficult to normalize potassium and calcium.Hyperkalemia and hypomagnesemia potentiate the cardiac neuromuscular irritability produced by hypocalcemia. Hypokalemia and hypermagnesemia protect against the effects of hypocalcemia. b) Beware that treatment of concomitant metabolic acidosis may further reduce ionized calcium level because both hydrogen ions and calcium are bound to albumin. As acidosis is corrected, hydrogen ions dissociate from albumin, allowing calcium to bind to albumin and further reducing the ionized calcium level.

4. Treatment:

Oral: CaCO3 500-1000 mg TID between (after) meals (to maximize absorption). Also consider vitamin D in patients with renal failure.

IV: max 10 mEq/hour. Symptomatic hypocalcemia (See signs above) — Patients should be treated immediately. Many patients have symptoms when their serum ionized calcium conc is < 2.8 mg/dL (0.7 mmol/L), or their serum total calcium conc (corrected) is ~ 7 to 7.5 mg/dL (1.8 mmol/L).

The most appropriate treatment, unless hypomagnesemia is documented, is intravenous calcium, in the form of 100 to 200 mg (2.5 to 5 mmol) of elemental calcium (1 to 2 grams of calcium gluconate) in 10 to 20 minutes. The calcium should not be given more rapidly, because of the risk of serious cardiac dysfunction, including systolic arrest. Such infusions do not raise the serum calcium concentration for more than two to three hours, and therefore should be followed by a slow infusion of calcium. The dose should be 0.5 to 1.5 mg/kg per hour. Either 10% CaGluc (93 mg [2.25 mmol] elemental Ca++/ 10 ml amp) or 10% CaCL (272 mg [6.75 mmol] elemental Ca++/ 10 ml amp) can be used, with the following recommendations: The calcium should be diluted in dextrose and water or saline, because concentrated calcium solutions are irritating to veins. Calcium gluconate is usually preferred to calcium chloride because it is less likely to cause tissue necrosis if extravasated.

Add 5 to 10 grams of Calcium gluconate to 1 liter of D5W.
Weight (kg) 0.5 mg/kg/hr 1 mg/kg/hr 1.5 mg/kg/hr
Elemental Ca++/hr converted to amt CaGluc/hr.
Example: 70kg patient (1 mg/kg/hr = 70 mg/hr.  70mg/(93 mg Ca++/gram CaGluc) = 0.753 grams CaGluc/hr
50 0.27 g CaGluc/hr 0.54 g CaGluc/hr 0.8 g CaGluc/hr
60 0.32 g CaGluc/hr 0.65 g CaGluc/hr 0.97 g CaGluc/hr
70 0.38 g CaGluc/hr 0.75 g CaGluc/hr 1.1 g CaGluc/hr
80 0.43 g CaGluc/hr 0.86 g CaGluc/hr 1.3 g CaGluc/hr
90 0.48 g CaGluc/hr 0.97 g CaGluc/hr 1.45 g CaGluc/hr
100 0.54 g CaGluc/hr 1.1 g CaGluc/hr 1.6 g CaGluc/hr
Continue calcium infusion until serum calcium level reaches 8 to 9 mg/dl.  As a guideline, the total calcium will increase by 0.5 mg/dl for every gram of calcium gluconate given intravenously.

Calcium gluconate: 1 gm in 50 ml D5W or NS.

Calcium chloride*: 1 gm in 100 ml D5W or NS     *Calcium chloride should not be given IM or SC because severe tissue necrosis may occur.

INFUSION RATE: Infuse over 30-60 minutes. Rapid administration may cause bradycardia, hypotension and vasodilation. Infiltration of IV calcium may cause severe tissue necrosis and sloughing. 

Calcium: (hypocalcemia):
Oral: ~1-2 grams/day (elemental Ca++) in 2-4 divided doses with food.
Example: CaCO3 500mg (200mg Ca++): 1-2 tabs qid.
IV: Symptomatic + corrected total < ~ 7 to 7.5 mg/dL. 1-2 grams CaGluc over 10-20 min x 1, then 0.5 to 1.5 mg/kg/hr elemental calcium. 70kg patient (1 mg/kg/hr) = 0.75g CaGluc/hour. Total calcium will increase ~ 0.5 mg/dl /gram of CaGluc given. Target level: 8 mg/dl.

Other Tables  top of page icon

To give you an idea of how different calcium supplements vary in calcium content, the following chart explains how many tablets of each type of supplement will provide 1000 milligrams of elemental calcium. When you look for a calcium supplement, be sure the number of milligrams on the label refers to the amount of elemental calcium, and not to the strength of each tablet. (Source:
Calcium supplement Strength of each tablet (in milligrams) Amount of elemental calcium per tablet (in milligrams) Number of tablets to provide 1000 milligrams of calcium
Calcium carbonate 625 250 4
  650 260 4
  750 300 4
  835 334 3
  1250 500 2
  1500 600 2
Calcium citrate 950 200 5
Calcium gluconate 500 45 22
  650 58 17
  1000 90 11
Calcium lactate 325 42 24
  650 84 12
Calcium phosphate, dibasic 500 115 9
Calcium phosphate, tribasic 800 304 4
  1600 608 2
Normal daily recommended intakes in milligrams (mg) for calcium are generally defined as follows:
Persons U.S. (mg) Canada (mg)
Infants and children
Birth to 3 years of age
400-800 250-550
4 to 6 years of age 800 600
7 to 10 years of age 800 700-1100
Adolescent and adult males 800-1200 800-1100
Adolescent and adult females 800-1200 700-1100
Pregnant females 1200 1200-1500
Breast-feeding females 1200 1200-1500

Getting the proper amount of calcium in the diet every day and participating in weight-bearing exercise (walking, dancing, bicycling, aerobics, jogging), especially during the early years of life (up to about 35 years of age) is most important in helping to build and maintain bones as dense as possible to prevent the development of osteoporosis in later life.

The following table includes some calcium-rich foods. The calcium content of these foods can supply the daily RDA or RNI for calcium if the foods are eaten regularly in sufficient amounts.
Food (amount) Milligrams of calcium
Nonfat dry milk, reconstituted (1 cup) 375
Lowfat, skim, or whole milk (1 cup) 290 to 300
Yogurt (1 cup) 275 to 400
Sardines with bones (3 ounces) 370
Ricotta cheese, part skim (1/2 cup) 340
Salmon, canned, with bones (3 ounces) 285
Cheese, Swiss (1 ounce) 272
Cheese, cheddar (1 ounce) 204
Cheese, American (1 ounce) 174
Cottage cheese, lowfat (1 cup) 154
Tofu (4 ounces) 154
Shrimp (1 cup) 147
Ice milk (3/4 cup) 132



National Institutes of Health, U.S. National Library of Medicine, DailyMed Database.
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