History and exam

Key diagnostic factors

common

haematuria

About 50% of patients present with visible haematuria usually preceded by upper respiratory tract infection (synpharyngitic nephritis) or gastroenteritis.[37]

Visible haematuria is usually painless but may occasionally be accompanied by loin pain and dysuria.

One third of patients present with asymptomatic invisible haematuria.[8][41][42]

Other diagnostic factors

common

proteinuria

Usually <2-3 g/day; patients rarely have nephrotic-range proteinuria.[37][49]

uncommon

hypertension

Patients rarely present with hypertension unless they have established chronic kidney disease. In the uncommon presentation of rapidly progressive glomerulonephritis, hypertension may be present. It is very rare to present with malignant hypertension.

oedema

Patients rarely present with significant oedema, unless accompanied by nephrotic-range proteinuria.

Risk factors

weak

family history of IgAN

Although IgAN is commonly sporadic, familial cases have been reported.[16][17][18][19] Genome-wide analysis has identified several genetic susceptibility loci, these do not map to the loci identified in the published familial IgAN kindreds.[20][21][22][23][36]

male sex

Affects males more than females with a ratio of at least 2:1 in North America and western Europe, but the sexes are equally affected in Asia.[37]

age 20 to 30 years

People in their 20s and 30s are more commonly diagnosed with IgAN than other age groups.[13][14]

Asian/white/native American ancestry

The incidence of IgAN varies substantially between people of different ethnicities or races.[13] IgAN is more frequent in Asian populations, but this may be influenced by variations in public health interventions, such as mass screening of urine in some Asian countries (Hong Kong, Japan, Korea, and Singapore), which is not common in other countries.[10] However, autopsy and genetic data also suggest that IgAN may be more common in Asian populations.[15]

In the US, IgAN is more common in Asian, white, and native American (the Zuni tribe in particular) people than in black people.[38][39]

IgA vasculitis

Kidney disease in IgA vasculitis (previously known as Henoch-Schönlein purpura [(HSP]) is indistinguishable from IgAN, but patients with IgA vasculitis demonstrate extra-renal manifestations, such as vasculitic skin rash, abdominal pain, and arthralgia.

chronic liver disease

Hepatic IgAN, in which mesangial IgA deposition is associated with chronic liver disease (particularly alcoholic cirrhosis), is the commonest form of secondary IgAN.[24][25] It is believed to be a consequence of impaired hepatic clearance of IgA. Mesangial IgA is a common autopsy finding in patients with chronic liver disease, but only a minority have clinical manifestations of renal disease other than invisible haematuria.

HIV infection

IgAN has been reported in association with HIV infection and AIDS.[26][27][28] The polyclonal increase in serum IgA, a feature of AIDS, has been cited as a predisposing factor.

The association is highly variable and the kidney disease is rarely of clinical significance.

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