Hypercalcaemia and hypocalcaemia Flashcards
Discuss the control of serum calcium?
Parathyroid Hormone: Increases serum calcium.
- Causes osteoclasts to reabsorb calcium from bones (bodys main Ca store)
- Increases reabsorption of Ca in the kidneys but decreases the reabsorption of Ph.
- Activates Vit D which increases the reabsorption of Ca in the intestine.
Calcitonin: Decreases serum calcium
- Inhibits osteoclast activity in the bone.
- Stimulates osteoblast activity.
- Inhibits reabsorption of Ca in the Kidney therefore more will be present in the urine.
- Inhibits reabsorption of Ca in the intestine.
What are the causes of raised serum calcium?
Hyperparathyroidism (Primary)
Non PTH mediated hypercalaemia:
- Malignancy
- Granulomatous conditions (sarcoidosis/TB)
Endocrine:
- Thyrotoxicosis
- Primary adrenal insufficiency
Iatrogenic:
- Thiazide diuretics (reduces calicum excretion)
- Vit D and A supplements
Familial:
- Familial Hypocalciuric hypercalcaemia
What is primary hyperparathryroidism and biochemically what will be seen?
Excess parathyroid hormone secretion directly from the gland due to:
- Solitary adenoma (80%)
- Hyperplasia
- Parathyroid maligancy (very rare less than 1%)
Biochemical:
- Raised serum calcium
- Phosphate will be low
- Normal or raised PTH (should be low due to negative feedback)
- ALP will be raised
By far the most common cause of hyperparathyroidism
What is secondary hyperparathryroidism and biochemically what will be seen?
It is hyperparathyroidism secondary low calcium caused by another condition.
Serum Ca will always be low normal or low, if it is raised it cannot be secondary hyperparathyroidism.
Causes: reduced intestinal absorption of calcium causing compensatory rise in PTH
- Vitamin D deficiency
- End stage chronic renal failure (active form of vitamin D is produced by the kidney)
Biochemical:
- Low normal/low serum calcium
- Raised PTH
- Low Vitamin D levels
- Raised Phosphate levels (if due to renal failure as the phosphate is not excreted)
What is tertiary hyperparathyroidism and biochemically what will you see?
Tertiary hyperparathyroidism occurs when there has been longstanding secondary hyperparathyroidism so that there is:
- Parathyroid hyperplasia
- The gland no longer responds to negative feedback even if the cause has been corrected.
Biochemically:
- High serum Ca (previously low)
- High PTH (as opposed to normal in primary)
- Low phosphate
- High ALP
What are the symptoms of hypercalcaemia?
Stones, bones, groans and psychic moans.
Stones:
- Renal stones
- Polyuria and polydipsia
Bones:
- Bone pain
- Pathological #
Psychic moans:
- Depression
Groans
- Abdo pain
- Nausea and vomiting
- Pancreatitis
- Dyspepsia and peptic ulcer disease (calcium increases secretion of gastric acid)
Describe the acute management of a patient with hypercalcaemia?
- Dilute Calcium by giving IV NaCl 0.9%
- IV bisphosphonates (pamidronate or zolendronic acid)
- Calcitonin if bisphosphonates not effective
What are the causes of hypocalcaemia?
Hypoparathyroidism frequently following:
- Surgery
- Radiotherapy
- Infiltartion e.g sarcoidosis or amyloidosis
Secondary hyperparathyroidism:
- Vitamin D deficiency
- Chronic renal failure
Other causes:
- Medication.
- Acute pancreatitis.
What are the signs and symptoms of hypocalcaemia?
Symptoms tend to correspond to the degree of hypocalcaemia. May be asymptomatic or symptoms may include:
- Paraesthesia (usually fingers, toes and around mouth).
- Tetany.
- Carpopedal spasm (wrist flexion and fingers drawn together).
- Muscle cramps.
- Seizures.
Signs:
- Prolonged QT interval which may progress to ventricular fibrillation (VF) or heart block.
Describe the management of hypocalcaemia?
Treat patients clinically not based on blood results unless very low and at risk of significant complications.
Treat where symptomatic (seizures, tetany) or at high risk of complications with a serum calcium <1.90 mmol/L.
Give 10 ml (2.25 mmol) of calcium gluconate 10% by slow intravenous (IV) injection.
