IgA nephropathy laboratory findings

In children and younger adults, the history and association with respiratory infection can raise the suspicion of IgA nephropathy directly. A urinalysis will show red blood cells, usually as red cell urinary casts. Proteinuria, usually less than 2 grams per day, also may be present. Other renal causes of isolated hematuria include thin basement membrane disease and Alport syndrome, the latter being a hereditary disease associated with hearing impairment. A kidney biopsy is necessary to confirm the diagnosis. The biopsy specimen shows proliferation of the mesangium, with IgA deposits on immunofluorescence and electron microscopy. However, all patients with isolated microscopic hematuria (i.e. without associated proteinuria and with normal kidney function) are not usually biopsied since this is associated with an excellent prognosis.

Other blood tests done to aid in the diagnosis include CRP or ESR, complement levels, ANA, ANCA and LDH. Protein electrophoresis and immunoglobulin levels can show increased IgA1 in 30% to 50% of all patients. may be normal or reduced. Tests such as electrolytes, renal function (creatinine, urea), total protein, serum albumin help in establishing the prognosis. Other tests such as bleeding time, full blood count, PT and PTT are done before performing a biopsy.