Calcium

Calcium

99% in bone

Remaining 1% in the blood

50% ionized

40% protein bound

10% chelated (citrate, bicarbonate, lactate, phosphate)

Normal  values

Serum/plasma Ca: 2.2-2.6mmol/l

Ionized Ca (biologically active form) 1.1-1.3mmol/l

Reduced levels in pregnancy

Functions

Muscular contraction

Cardiac action potential and pacemaker activity

Ciliary motility

Blood coagulation

Bone formation

Hormone Regulation

Ionized Hypocalcaemia > PTH secretion > Ca mobilization AND VitD synthesis in Kidney (increased gut and renal absorption)

Hypercalcaemia
Classification according to total serum Calcium

normal             2.2-2.6mmol/l

mild                 2.6-3.0 mmol/l

moderate         3.0-3.4 mmol/l

severe              >3.4mmol/l

Serum Ca Correction for low albumin 

+0.2mmol/l Ca for every 10g/l albumin below 40g/l

Distribution

99% bound to bones

1% in extracellular space

50% ionized (biologically active)

40% bound to proteins (mainly albumin)

10% bound to anions

Equilibrium dependent on pH and protein concentration

Symptoms

Neuro: weakness, drowsyness, coma

GIT (ulcer, nausea, vomiting, peptic ulcer disease, pancreatitis)

CV (arrhythmia, short QT, U-wave, hypotension)

stones (nephrolithiasis, nephrocalcinosis)

bones (osteomalacia, osteoporosis, arthritis)

Causes

50% Hyperparathyreoidism

  • solitary adenoma
  • endocrine neoplasia
  • Lithium Therapy

40% Malignancy

  • solid tumor with metastases
  • haematological tumors (mult myeloma. lymphoma)

10% Other Causes

  • Drugs (Vit D. Lithium, Thiazides, Calcium)
  • Increased bone turnover (Hyperthyroidism, immobility
  • Familial (familiary hypocalciuric hypercalcaemia)
  • milk-alkali syndrome

Diagnosis

Parathyroid hormone

If PTH high: Primary Hyperparathyreoidism

If PTH low: Malignancy or other cause

Urinary Calcium

Excretion high in Primary Hyperparathyreoidism, and malignancy

Excretion low in familiary hypocalciuric hypercalcaemia, thiazides and milk alkali syndrome\

Treatment

Volume expansion

Normal saline administration

Increase excretion

 Loop diuretics

Inhibit bone resorption

Bisphosphonates

zoledronic acid 4mg over 30/60 iv

pamindronate 60-90mg 4/24

inhibits osteoclast mediated bon resorption

Steroids (in Vit D induced hypercalcaemia)

            hydrocortisone 100-300mg/day or prednisolone 40-60mg/day

            inhibit VitD production

Calcitonin

Dialysis

            rarely needed

Hypocaliaemia

Clinical Presentation

Mild degree usually asymptomatic

Ionized Ca 0.8mmol/l may cause neuromuscular Symptoms (increased irritanbility)

Causes

Hypoparathyreoidism

  • Sepsis
  • Burns
  • Surgical removal

Chelation

  • Alkalosis (binding to Albumin)
  • Pancreatitis
  • Rhabdomyolysis
  • Citrate (blood products)

Hypovitaminosis D

  • Liver or kidney disease
  • low intake (malnutrition/malabsorption)

Drug induced

  • EDTA
  • Diuretics
  • Ethylene Glycol (forms Ca oxalate crystals in urine)

With metabolic Acidosis

  • Rhabdomyolysis
  • Pancreatitis
  • Tumor lysis
  • ethylene glycol intoxication

Symptoms

CNS

cramps, tetany, seizure myopathy

Cardiovascular

Arrhythmia, Hypotension

Management

ABC

iv Ca 

CaGluconate: 93mg in 10ml 10%

CaChloride: 272mg in 10ml 10%

CaCl causes more tissue necrosis when extravasated >Therefor preferrably CaGluconate

Bloods

Serum Ca, PTH, Mg, PO4,