Routine Laboratory Testing for Pseudogout
For patients with suspected or confirmed pseudogout, screen for underlying metabolic disorders with serum calcium, magnesium, alkaline phosphatase, ferritin, and thyroid-stimulating hormone (TSH), as these conditions are associated with calcium pyrophosphate deposition disease and may require specific treatment. 1, 2
Essential Metabolic Screening
The primary goal of laboratory testing in pseudogout is to identify treatable underlying metabolic conditions that predispose to calcium pyrophosphate crystal deposition:
- Serum calcium and parathyroid hormone (PTH) should be measured to screen for primary hyperparathyroidism, which is a well-established association with pseudogout 1, 3
- Serum magnesium should be checked, as hypomagnesemia is found in nearly 30% of pseudogout patients with laboratory abnormalities 2
- Serum ferritin and iron studies are recommended to screen for hemochromatosis, an important metabolic cause of pseudogout 1
- Alkaline phosphatase should be measured as part of the metabolic evaluation 2
- TSH should be obtained to screen for thyroid disorders associated with calcium pyrophosphate deposition 2
Renal Function Assessment
- Serum creatinine and blood urea nitrogen (BUN) should be measured, as chronic renal failure is associated with pseudogout and may present with atypical features 4
- Chronic kidney disease increases the incidence of chondrocalcinosis, particularly in patients over age 60 (15.8% incidence in dialysis patients) 4
Important Clinical Context
- Laboratory abnormalities are frequent in both pseudogout patients and age-matched controls, so results must be interpreted in clinical context 2
- Elevated PTH, hypomagnesemia, and hypocalcemia together account for almost 30% of abnormal laboratory findings in pseudogout patients 2
- The presence of pseudogout may be the first clinical clue to an unsuspected metabolic disease requiring specific treatment 1
Common Pitfalls to Avoid
- Do not assume pseudogout is idiopathic without screening for metabolic causes—identifying hyperparathyroidism or hemochromatosis changes management fundamentally 1
- Be aware that postoperative pseudogout can occur after parathyroidectomy, typically within 48 hours of surgery 3
- In younger patients (under age 50) with pseudogout, metabolic screening is particularly important as the condition is less common in this age group and more likely to have an underlying cause 1, 4