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Clinical symptoms

• General—weakness, lassitude, weight loss.

• Mental changes—impaired concentration, drowsiness, personality change and coma.

• GIT—anorexia, nausea, vomiting, abdominal pain (peptic ulceration and pancreatitis are rare complications).

• Genitourinary—polyuria, polydipsia.

Clinical effects

• Cardiovascular—5 QT interval on ECG, cardiac arrhythmias and hypertension.

• Renal—dehydration, renal failure and renal calculi.

Haematological causes

1. Myeloma.

2. High grade lymphoma.

3. Adult T-cell leukaemia/lymphoma (ATLL).

4. Acute lymphoblastic leukaemia.

Hypercalcaemia occurs in other clinical situations including metastatic carcinoma of breast, prostate and lung. Theories for occurrence in haematological malignancy include increased bone resorption mediated by osteoclasts under the influence of locally or systemically released cytokines such as PTH-related peptide, TGF, TNF-a, M-CSF, interleukins and prostaglandins. Increased intestinal absorption of calcium secondary to increased 1,25-hydroxycholecalciferol.

Normal range for plasma [Ca2+] 2.12-2.65mmol/L. 40% of plasma Ca2+ is bound to albumin. Most laboratories measure the total plasma Ca2+ although only unbound Ca2+ is physiologically active. For accurate measurement of plasma or serum Ca2+ blood sampling should be taken from an uncuffed arm, i.e. without the use of a tourniquet.

Correct for albumin

Albumin <40g/L corrected calcium = (Ca2+) + 0.02 [40-(Albumin)] Albumin >45g/L corrected calcium = (Ca2+) - 0.02 [(Albumin)-45]

Management

1. Rehydrate with normal saline 4-6L/24h.

2. Beware fluid overload—use loop diuretics and CVP monitoring if necessary.

3. Stop thiazide diuretics and consider regular loop diuretics.

4. Give bisphosphonates e.g. disodium pamidronate 60-90mg IV stat (see table).

5. Treat underlying malignancy.

6. Consider dialysis if complicating factors (CCF, advanced renal failure).

7. Other therapeutic options:

- Calcitonin 200IU 8-hourly.

- Corticosteroids (e.g. prednisolone 60mg/d PO).

- Mithromycin 25|jg/kg IV x 3 weekly.

- Plicamycin.

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