Factors increasing the risk of urinary tract infections in old age include reduced T lymphocyte regulation, decreased B lymphocyte antibody synthesis, impaired killer T cell function and slowed neutrophil chemotaxis. More practical causes for a high incidence of urinary infections are multiple pathology and poor nutrition. In women, a low oestrogen level increases the intravaginal pH, resulting in the lactobacillus being replaced by a pathogenic agent. Faecal stasis may also increase the risk of a urinary infection. The presentation and severity of a urinary infection are affected by intercurrent disorders such as diabetes mellitus, poor bladder control, concurrent medication and cognitive impairment. Other relevant but less common disorders are bladder calculi and tumours. Common signs of pyouria in old age are urinary incontinence, anorexia, lethargy and confusion. The infection may even be asymptomatic and this is discussed later.