Hypocalcemia

DR IYAN DARMAWAN

Background

Presentations vary widely

Unrecognized and untreated severe hypocalcemia leads to

significant morbidity and death

The most common cause is hypoalbuminemia

Underlying conditions (cirrhosis, malnutriton, nephrosis, burns,

chronic illness and sepsis) low serum calcium is simply due to

hypoalbuminemia

Other causes include: Vit D deficiency or resistance, PTH deficiency

or resistance, surgical effects, medication, hyperphosphatemia, hypomagnesemia etc.

Homeostasis and Physiological Role

Total serum Calcium 8.6-10.2 mg/dl (2.15-2.55 mmol/L)

Ionized Calcium 4.4-5 mg/dl (1.1 -1.25 mmol/L) (Note: 1 mmol Ca++ = 2 mEq Ca++ )

Bone metabolism, nerve conducton, intracellular signaling, coagulation cascade,

regulation of secretory function

Total body distribution 99% bone; 1% serum

Plasma protein binding (80% with albumin)

Regulated by vitamin D, Phosphorus and PTH

Dietary intake : enteral 100-1200 mg/day; PN 10-15 mEq/day

Todd W. The A.S.P.E.N. Fluids, Electrolytes, and Acid-Base Disorders Handbook. ASPEN 2015. pp 142-164

Prevalence of Hypocalcemia

18% hospitalized patients; up to 85% ICU patients (15-88%)1

Fifty percent of hypocalcemic patients in the ICU have sepsis, as opposed to 25% of normocalcernic patients.2

Hypocalcemic patients are more likely to need vasopressor support

(41% of hypocalcernic patients as opposed to 14% normocalcernic

patients) 3.

The mortality rate of hypocalcernic critically ill patients is significantly

greater than that of normocalcernic patients (44% vs. 17%).2

1. Zaloga GP: Hypocalcemia in critically ill patients. Crit Care Med 1992, 20:251-262

2. Desai TK, Carlson RW, Geheb MA. Prevalence and clinical implications of hypocalcernia in acutely ill patients in a medical intensive care setting. Am JMed

1988; 84:209-14.

3. Desai TK, Carlson RW, Thill-Baharozian, et al. A direct relationship between ionized calcium and arterial pressure among patients in an intensive care unit. Crit

Care Med 1988:16:578-82

Clinical Presentation of Hypocalcemia

Mild to Moderate Severe

Total Ca 7.5-8.5 mg/dl or < 7.5 mg/dl or

1.9-2.1 mmol/L < 1.9 mmol/L

Ionized Ca 4-4.5 mg/dl or < 4 mg/dl or1-1.2 mmol/L < 1 mmol/L

PresentationParesthesia, muscle cramps,mental status changes, Chovestek's signTrousseau's sign, and hypotension

tetany, acute heart failure, andArrhythmia

1. Kraft MD, Btaiche IF, Sacks GS, et al. Treatment of electrolyte disorders in adult patients in the intensive care unit. Am J Health Syst Pharm. 2005;62:1663-1682

2. Guise TA, Mundy GR. J Clin Endocrinol Metab. 1995;80 :1473– 1478

3. French S, Subauste J, Geraci S. Calcium abnormalities in hospitalized patients. South Med J 2012;105:231-7

Trouseau’s sign and Chvostek’s sign

Inflate cuff to SBP will trigger carpopedal spasm

Diagnosis

Assess albumin since serum alb < 4 g/dl, should adjust total serum

calcium calculation

Corrected Total Serum Ca (mg/dl)= Measured Total Serum Ca (mg/dl) + [0.8 mg/dl x (4.0 g/dl – measured albumin (g/dl)]

Example: Measured Total serum Ca 6 mg/dl; alb 2.7 g/dl → Corrected Total serum Ca = 6 + 0.8 x 1.3 = 7.04 mg/dl (moderate

hypocalcemia)

Ionized serum calcium < 4.5 mg/dl ( < 1.12 mmol/L) should be used

in critical care setting because albumin-adjusted esdtimation is not reliable

Goals of Therapy

Total Serum Ca 8.6-10.2 mg/dl (2.15-2.55

mmol/L) or

Ionized serum Ca > 4.5 mg/dl or > 1.12 mmol/L

Manage underlying illness

Management

Mild to moderate : Oral supplementation

IV Calcium

Intermitten iv boluses for severe symptomatic (total serum ca < 7.5

mg/dl or < 1.9 mmol/L) or ionzied Ca < 4 mg/dl or < 1 mmol/L)

Symptocatic hypocalcemia is an emergency

Administer 1 g Calcium chloride or 2-3 g Ca Gluconate iv over 5 -10

minutes

Asymptomatic hypocalcemia 2-4 g Ca gluconate (1 g/hour)

Refractory hypocalcemia: Continuous infusion of elemental calcium

Others: consider vit D preparations

Calcium Parenteral Products

CALCIUM PARENTERAL: PRODUCTS

Product Available solutions Elemental

calcium content

per 1000 mg of

solution

Route of

Administration

Calcium

gluconate

10% 92 mg (4.65 mEq) Peripheral/central

Calcium chloride 10% 272 mg (13.6 mEq) Central

• Avoid admixing into parenteral solutions containing bicarbonate or

phosphate

• Maximum infusion rateshould not exceed 1.4 mEq of Calcium per minute

Treatment of refractory/severe HypoCalcemia

Elemental Calcium iv 100-300 mg over

5-10 minutes

(1 g Ca Chloride or 3 g Ca Gluconate)

Continue Elemental Calcium iv

(0.25-2 mg/kg/h)

Ionized Calcium normalized?

Symptoms not rersolved

Yes

Maintainance Elemental Calcium

iv (0.3-0.5 mg/kg/h) Consider Oral Calcium

No

Check Ionized Calcium every 1-4 h

Todd W. The A.S.P.E.N. Fluids, Electrolytes, and Acid-Base Disorders Handbook. ASPEN 2015. pp 142-164

Monitoring

Asymptomatic patients treated with oral supplements require

assessment every 24-48 hours (inpatient) or every 2-3 months

(outpatient)

Acute, symptomatic aggressively treated should be monitored 4-6

hourly until normal levels are obtained

Given the variety of causes, consultations may include or or more of

the following: internist, endocrinologst, intensivist, surgeon,

oncologist, nephrologist, dietitian and toxicologist