Management (and Pathophysiology) of Hypocalcemia

What is the normal range of serum Ca2+ ?

8.4 - 10.2 mg/dL

What is HYPOcalcemia in terms of serum Ca2+ ?

< 8.4 mg/dL

What is HYPOcalcemia in terms of ionized Ca2+ ?

< 1.12 mmol/L

What is the pathophysiology of HYPocalcemia? (5)

1. Vit D Deficiency

2. Hypoparathyroidism

3. Hypomagnesemia

4. Hungry Bone Syndrome

5. Drug-induced hypocalcemia

When Vitamin D is present, net serum Ca2+ increases or decreases?

Vit D causes increase

When PTH is present, net serum Ca2+ increases or decreases?

PTH causes increase

When Calcitonin is present, net serum Ca 2+ increases or decreases?

Calcitonin causes decrease

When FGF23 is present, net serum Ca2+ increases or decreases?

NO CHANGE/NO EFFECT (phos only)

Why would a Vitamin D deficiency (1) be detrimental to calcium levels?

necessary for optimal absorption of calcium and phosphorus (GI, kidney, Bone release)

Why would hypoparathyroidism (2) be detrimental to calcium levels?

lack of PTH release, less kidney reabsorption and bone release

Why would hypomagnesemia (3) be detrimental to calcium levels?

less magnesium → less PTH secretion → resistance of target organs to the actions of PTH

Why would Hungry Bone Syndrome (4) be detrimental to calcium levels?

bond hungrily incorporates ca2+ and phos from blood to recalcify bone

What major drugs can causes drug-induced hypocalcemia?

furosemide, calcitonin (inhibitors bone resorption and reduced tubular reabsorption of calcium), bisphosphonates, cinacalcet

What is the clinical presentation of acute hypocalcemia?

neuromuscular excitability, tetany, muscle cramps, abdominal pain, seizures, Chvostek (facial twitch with light stimulation) and Trousseau signs (wrist bent with slight stim), EKG changes (prolonged ST segment)

What is pseudocalcemia?

when there’s a low albumin count (which Ca2+ binds to when unionized), making total serum Ca2+ appear low when there is a normal amount of ionized/unbound Ca2+

What is the corrected Ca2+ equation?

Ca + 0.8(4 - albumin)

When do you need to calculate corrected calcium?

when albumin < 3.5

What kind of calcium level can you measure to see how much unbound Ca2+ (active) there really is?

free/ionized Ca2+ (should be 1.12 - 1.3 mmol/L)

Hypocalcemia Management includes treating underlying causes and _______

Calcium Repletion

What is the recommended dietary allowance of calcium/day for either gender 19 - 50 yo?

1000 mg/day

What is the recommended dietary allowance of calcium/day for men 51 - 70 yo?

1000 mg/day

What is the recommended dietary allowance of calcium/day for women 51 to 70 years?

1200 mg/day

What is the recommended dietary allowance of calcium/day for women and men greater than 70 years?

1200 mg/day

What is the recommended dietary allowance of calcium/day for those who are pregnant or lactating and 19 to 50 years?

1000 mg/day

What are the calcium oral products that we have learned, and in what context?

Hyperphosphatemia: calcium-containing phosphate binders

1. calcium carbonate (Tums, Os-Cal)

2. calcium acetate (Phoslo - Rx)

What are the calcium IV products, and in what context?

Hyperkalemia (C a BIG K Drop) and Hypermagnesemia

1. calcium chloride (CENTRAL)

2. calcium gluconate (PERIPHERAL)

Which ROA is preferred in mild, asymptomatic and chronic hypocalcemia?

oral

What is the oral dose of calcium for mild, asymptomatic and chronic hypocalcemia?

1500 - 2000 mg Ca2+ daily in divided doses (calcium carbonate or calcium citrate)

What percentage of calcium does the carbonate salt have?

40% (PO, SL)

What percentage of calcium dose the citrate salt have?

21% (PO only)

How much more does calcium chloride have than calcium gluconate?

3x more elemental calcium

When and how is is calcium chloride given?

only acute situations as a slow injection IV via central line

How is calcium gluconate given?

slow injection through central OR peripheral IV

What monitoring should be done after administering oral formulations?

N/V

What monitoring should be done after administering IV formulations?

burning sensation, vasodilation, skin/vein necrosis

What potential drug interactions can happen after administering calcium products?

phosphorous, fluoroquinolone antibiotic, doxycycline (antibiotic)

If the patient’s corrected serum calcium < 8.6 mg/dL or ionized calcium < 4.4 mg/dL but they also are symptomatic and have acute hypocalemia, what treatment should be started?

IV calcium chloride or gluconate bolus over 10 minutes

If the patient’s corrected serum calcium < 8.6 mg/dL or ionized calcium < 4.4 mg/dL but they also are asymptomatic and have acute hypocalemia, what treatment should be started?

consider IV calcium gluconate bolus at 1 gram/hour

If the patient’s corrected serum calcium < 8.6 mg/dL or ionized calcium < 4.4 mg/dL but they also are asymptomati and have chronic hypocalemia, what treatment should be started?

oral calcium 1-3 g/day

When ionized Ca2+ is 1-1.2 mmol/L, what is its severity?

mild-to-moderate (asymptomatic)

What is the bolus dosing for for 1-1.12 mmol/L?

Ca gluconate 1-2 g over 30 -60 min; may repeat q6H prn

When ionized Ca2+ is ≤ 0.99 mmol/L, what is its severity?

severe

What is the bolus dosing for ionized Ca ≤ 0.99 mmol/L?

Ca Chloride 1-2 g (CENTRAL) OR Ca gluconate 3-4 g (PERIPHERAL)

both over 10 minutes (may repeat PRN)

Which statements are true regarding calcium products?

1. Ca carbonate contains 40% elemental calcium, whereas calcium citrate contains 21% elemental calcium

2. Ca carbonate is only administered PO, whereas calcium citrate can be administered PO or IV

3. Ca chloride is 3 times more potent than calcium gluconate

4. ca carbonate should be taken with food for better absorption

5. Ca citrate should only be administered through a central IV line

1,3,4