Diagnostic Tests For Pseudogout

X-rays show a typical calcification of joint sufaces (articular cartilage) due to shedding of pyrophosphate crystals.

This is called "chondrocalcinosis". Here the menisci between the thigh bone and the tibial bone show spurs of calcification.

Samples under the polarized light microscope show the rhomboid, square or rod-shaped crystals, which makes the diagnosis. Here is another image of the kind of geometrical shapes that are found with these crystals.Such samples are either obtained from centrifuged synovial fluid samples or from direct biopsies and can often also be found in white blood cells from the inflamed tissue.

As iron storage disease (hemochromatosis) can trigger pseudogout, a serum ferritin level would be desirable, if this is clinically suspected.

Other tests might include a TSH test to rule out hypothyroidism and occasionally a parathyroid hormone test, if there is an elevated serum calcium level and there is suspicion of a parathyroid adenoma. In the case of clinical evidence of amyloidosis the specialist might consider a rectal biopsy or a subcutaneous fat pad aspiration to do special staining tests and examination under a polarizing microscope to detect the characteristics of amyloid.

Disclaimer:

This outline is only a teaching aid to patients and should stimulate you to ask the right questions when seeing your doctor. However, the responsibility of treatment stays in the hands of your doctor and you.

References:

1. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 55.

2. ABC of rheumatology, second edition, edited by Michael L. Snaith , M.D., BMJ Books, 1999.

3. Goldman: Cecil Textbook of Medicine, 21st ed.(©2000)W.B.Saunders

4. Ferri: Ferri's Clinical Advisor: Instant Diagnosis and Treatment, 2004 ed., Copyright © 2004 Mosby, Inc.

5. Rakel: Conn's Current Therapy 2004, 56th ed., Copyright © 2004 Elsevier

Last Modified: March 17, 2012