Dr Alli Madden1, Dr Andrea Huang1,2,3, Dr Daniela Potter1,3,4, A/Prof Renuka Shanmugalingam1,4
1Liverpool Hospital, LIVERPOOL, Australia, 2University of Sydney, Camperdown, Australia, 3University of New South Wales, Kensington, Australia, 4Western Sydney University , Parramatta, Australia
Biography:
Dr Alli Madden is a first year nephrology advanced trainee with interests in general nephrology and obstetric medicine
Background:
Cryoglobulinaemic vasculitis is a systemic inflammatory syndrome affecting small vessels, presenting with non-specific symptoms including renal impairment. The diagnosis is challenging, with high false-negative rates of up to 40%; serum immune complex levels vary, and testing is reliant on observation of precipitation at 4°C and, typically, dissolution at 37°C. We present two cases of cryoglobulinaemic vasculitis with initial non-diagnostic results.
Case 1:
A 74-year-old woman presented with purpuric rash and new onset haemoproteinuria with renal impairment. Rheumatoid factor was raised (270IU) and C4 undetectable (<0.04). Renal biopsy confirmed small vessel vasculitis. Initial testing for cryoglobulins was non-diagnostic as the precipitate did not re-dissolve at 37°C. Given the high clinical suspicion, testing was repeated. Cryoglobulins precipitated at 4°C, and dissolved only when sample was heated to 56°C.
Case 2:
A 77-year-old man was referred to the renal clinic with a two-month history of petechial rash and renal impairment, associated with an elevated rheumatoid factor (452IU) and undetectable C4. Renal biopsy favoured mixed cryoglobulinaemic glomerulonephritis. Serological testing noted a precipitate that did not dissolve at 37°C, reported as inconsistent with cryoglobulin. Due to clinical concern, repeat testing noted dissolution of the precipitate at 56°C.
Conclusion:
We posit that some initial non-diagnostic cryoglobulin results may be due to a precipitate with an increased thermal amplitude, requiring higher temperatures to observe dissolution. Initial negative results discordant with high clinical suspicion warrant further testing at increased temperatures. In the above cases, treatment was commenced based on clinical suspicion. Waiting for confirmatory testing may lead to a delay in diagnosis given the variability in dissolution points