What is the role of lab testing in the diagnosis of Charcot arthropathy?

Updated: Jun 21, 2018
  • Author: Mrugeshkumar Shah, MD, MPH, MS; Chief Editor: Vinod K Panchbhavi, MD, FACS  more...
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Answer

The white blood cell (WBC) count with differential often is ordered to help distinguish between Charcot arthropathy and osteomyelitis. The WBC count is elevated when infection is present, and often, a left shift is revealed with infection. However, the WBC count is a nonspecific marker for inflammation, and the results may be elevated in patients with Charcot arthropathy.

The erythrocyte sedimentation rate (ESR) is used to help distinguish between Charcot arthropathy and osteomyelitis and is often elevated in infection; however, it is a nonspecific marker for inflammation.

The basic metabolic profile (Chem 7) is ordered to identify the underlying etiology. Elevated levels of creatine and of blood urea nitrogen (BUN) could suggest renal disease, whereas an elevated glucose level could suggest diabetes.

Other tests

Additional tests may be ordered, depending on the patient's history, physical examination results, and risk factors.

Glycosylated hemoglobin (HbA1c) indicates the level of hyperglycemic control in diabetes. Elevated HbA1c indicates poor hyperglycemic control. Hyperglycemia can cause nonenzymatic collagen glycosylation, which can lead to laxity in ligaments and unstable joints.

Levels of alkaline phosphatase, calcium, phosphorus, and parathyroid hormone (PTH) can help the physician to identify bone diseases, such as Paget disease. Hypercalcemia may be indicative of cancer or metastases.

Vitamn B12/folate deficiency could suggest an etiology of peripheral neuropathy. This deficiency also could suggest chronic alcoholism.

Findings of liver function tests/coagulation studies may suggest chronic alcoholism.

Rapid plasma reagin (RPR)/fluorescent treponemal antibody–absorption (FTA-ABS) tests aid in the diagnosis of syphilis.


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