Hypocalcaemia

Last updated 20.10.13

 

Definition

- Serum Calcium (Ca) <2.25mmol/L

 

Features

- Calcium levels must be corrected with albumin

-  Low albumin = low serum Ca (bound)

-  Around 50% of calcium bound to albumin

-  May cause decreased Anion gap

-  Severe: Ca <1.80 (corrected) + S/S

-  Moderate: Ca 1.80-2.00mmol/L (corrected) + symptoms +/- signs

-  Mild: Ca >2.00mmol/L + nil S/S

 

Causes

-  Thyroidectomy

-  Parathyroidectomy, destruction, agenesis, AID, hypoparathyroidism

- Pseudohypoparathyroidism

-  CRF

-  Drugs: calcium chelators, bisphosphanates, Phenytoin, Ketoconazole

-  Acute Pancreatitis

-  Rhabdomylolysis

-  Toxic Shock Syndrome

-  Malignancy

-  Vitamin D deficiency or resistance

-  Hypomagnesmia

 

Associated S/S

-  Seizures

-  Laryngospasm, bronchospasm

-  Severe

-  Cramps, carpopedal spasm

- Paresthesia

-  Chvostek sign

- Trousseau sign

-  Moderate

-  Cramps, paresthesia

-  Usually nil signs

-  Mild

-  Usually asymptomatic

-  Chronic

-  Dilated Cardiomyopathy

-  Subscapular cataracts

-  Papilloedema

-  Ectopic calicification

-  Dementia, confusion

 

Ix

-  CMP

-  Corrected calcium

-  If critically ill or acid-base disorders may need to measure ionised calcium without using a tourniquet

-  PTH

-  Vitamin D

-  U&E

-  Creatinine: CRF

-  LFT

-  Usually asymptomatic

-  Albumin for corrected calcium levels

-  ALP

-  +/- ECG: prolonged QT interval

 

Interpretation

-  CRF: high P04, PTH, ALP & Cr

-  Hypoparathyroidism: high P04, low PTH, normal ALP

-  Pseudohypoparathyroidism: high P04 & PTH

-  Vitamin D Deficiency: low P04 & Vitamiin D, high PTH & ALP

 

Mx

Caltrate 1000-1500 PO Daily

+/- Vitamin D

-  May require Calcitriol in CRF (renal conversion of Vitamin D)

+/- Magnesium

-  Severe

-  10-20ml Calcium Gluconate 10% in 50-100ml NS or 5% Dextrose IV over 5-10min

-  Caltrate 1200mg PO BD

-  Then 10ml Calcium Gluconate 10% in 500ml 5% Dextrose 6/24

-   Adjust as per CMP 6/24

-   Cease after 48hrs when Ca >2mmol/L

-   CMP for Ca 6/24 post cesing infusion then BD

-  Moderate

-  Caltrate 1000-1500mg PO Daily

-  CMP for Ca next day

-  If stable repeat CMP for Ca 1/52

-  Mild

-  Observe

-  CMP for Ca next day

-  If stable repeat CMP for Ca 1/52

-  Normocalcaemic + S/S

-  Caltrate 1000-1500mg PO Daily

-  Repeat CMP for Ca

 

 

 

References

 

BMJ: Investigation Hypocalcaemia