Bone Investigation

Routine Bone Profile : Standard calcium, phosphate, albumin, alkaline phosphatase

Routine Rheumatology Profile : Rheumatoid factor

Common Diagnostic patterns

Osteoporosis Osteomalacia Pagets Disease of Bone
Calcium normal
Phosphate normal
Alkaline phosphatase normal
Calcium low/normal
Phosphate low/normal
Alkaline phosphatase
Calcium normal (but may be elevated with immobility)
Phosphate normal
Alkaline phosphatase

Common causes

Hypercalcaemia Hypocalcaemia
Metastatic cancer with bony metastases (breast, lung, kidney, stomach and prostate)
Renal failure
Hyperparathyroidism
Myeloma
Sarcoidosis
Artefactual due to prolonged venous stasis with tourniquet
Vitamin D deficiency due to poor diet/malnutrition
Renal failure
Hypoparathyroidism (eg post thyroid surgery)

Arthritis

Type  
Septic arthritis Urgent referral for blood and joint aspirate culture
Rheumatoid arthritis Rheumatoid factor
Plasma viscosity to monitor disease activity
Pyrophosphate arthritis Microscopy of aspirated joint fluid
Gout Plasma uric acid estimations are most valuable in the monitoring of allopurinol therapy rather than in the diagnosis of gout; since raised uric acid concentrations within the joint cavity rather than in blood are the crucial process and patients with acute gout can have NORMAL plasma uric acid concentrations.

Bone pain

Diagnosis Investigation indicated
Generalised osteomalacia X-ray and chemistry as above
Myeloma protein AND urine electrophoresis
Paget's disease and immobilisation X-ray relevant bone, alkaline phosphatase and bone isoenzyme
Malignant metastases Bone scan or X-ray

Chronic inflammatory arthritides are frequently associated with either micro- or normocytic anaemia. Ferritin concentrations may be spuriously high as ferritin is an acute phase reactant and is raised in inflammatory states c.f. ESR & C-reactive protein.


Page updated: 20/04/10 | Updated by: Dr. Julian Barth

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