1. PTH
   • Produced by parathyroid glands: 84AA
   • Effects:
   1. Bone: stimulates osteoclasts [IL-1] + releases calcium and phosphate into circulation
   2. Kidney: (1) increased calcium resorption, increased phosphate loss (2) stimulates 1-alpha-OH activity of kidney
2. Vitamin D
   • Formed from cholesterol, metabolised in liver and kidney
   • Effects:
   1. Bone: stimulate osteoblast proliferation
   2. Kidney: calcium + phosphate resorption
   3. Gut: Enhances gut absorption of calcium + phosphate

1. Calcitonin
   
   • From thyroid parafollicular cells: 32AA
   • Effects
   1. Bone: Inhibit osteoclast activity
   2. Kidney: Increases calcium excretion

• Primary hyperparathyroidism (adenoma of PTH gland)
• Malignancy: bronchogenic carcinoma, secondaries to bone
• Renal calculi, pancreatitis
• Renal transplant with tertiary hyperparathyroidism

• Post thyroid surgery (removal of parathyroid glands)

• Calculi - renal
• Increased gastric acid secretion
• Risk of pancreatitis
• Constipation
• Impairment of tubular function - polyuria, polydipsia, dehydration
• Tiredness, lethargy, psychosis
• ECG: shortened QT, increased PR, heart block, flattened T-waves 

• Neuromuscular irritability - parasthesia (Chvostek's facial tap; Trousseau's arm spasm)
• Muscular cramps
• Tetany

Acute hypercalcaemia (3.0-3.5mmol/l)

1. Identify and treat cause
2. Cardiac monitoring
3. Rehydration; to prevent overload, CVP monitoring; frusemide for calcium diuresis
4. Bisphosphonate infusion (Pamidronate - rapidly reduce serum calcium)
5. Calcitonin
6. High dose steroids
7. Urgent surgery in cases due to hyperparathyroidism 

1. Identify and treat cause
2. Cardiac monitoring
3. Adequate fluid resuscitation
4. 10ml 10% calcium gluconate + 10-40mls in saline infusion over 4-8hours
5.