From the Guidelines
Pseudogout diagnosis relies primarily on joint fluid analysis showing calcium pyrophosphate dihydrate (CPPD) crystals, which appear rhomboid-shaped and weakly positively birefringent under polarized light microscopy. Laboratory tests should include serum calcium, phosphate, magnesium, alkaline phosphatase, and thyroid function tests to identify underlying metabolic disorders that can predispose to CPPD crystal formation 1. Serum uric acid should also be measured to differentiate from gout, though levels may be normal in pseudogout.
Key Laboratory Findings
- X-rays can reveal chondrocalcinosis (calcification of cartilage), particularly in knee menisci, wrist triangular fibrocartilage, and pubic symphysis, with a rating of 9 for appropriateness in suspected inflammatory arthritis, including pseudogout 1
- Elevated inflammatory markers like ESR and CRP may be present during acute attacks
- Underlying conditions like hyperparathyroidism, hemochromatosis, hypomagnesemia, and hypophosphatasia should be ruled out as they can contribute to CPPD deposition disease
Diagnostic Approach
- Joint fluid analysis is the gold standard for diagnosis
- Laboratory tests and imaging studies can support the diagnosis, but are not definitive alone
- A comprehensive diagnostic approach should include a combination of laboratory tests, imaging studies, and clinical evaluation to distinguish pseudogout from other arthritides 1
From the Research
Pseudogout Labs
- The diagnosis and treatment of pseudogout are crucial in primary care settings 2
- Pseudogout, also known as calcium pyrophosphate dihydrate (CPPD) crystal-related arthropathies, presents particular management problems in clinical practice due to its common occurrence in older patients with multiple medical comorbidities 3
- Routine investigations used in the diagnostic workup of pseudogout include laboratory tests to detect CPPD crystals 3
- Unlike gout, there are no agents available that have been shown to decrease crystal load in CPPD-related joint disease, and current treatment approaches are mainly directed at relieving the symptoms of joint inflammation 3
- The use of colchicine as a prophylactic agent in managing recurrent attacks of pseudogout is highlighted, as well as its potential effects on the NACHT, LRR and PYD domains-containing protein 3 (NALP-3) inflammasome of the innate immune system 3
- Laboratory tests may also be used to rule out other conditions, such as gout, and to monitor the patient's response to treatment 4, 2
- Acute treatment of pseudogout is similar to acute gouty arthritis treatment, but there is no standard regimen for long-term chronic therapies of pseudogout 2