Renal medicine - Special interest

Glomerulonephritis is the second most common cause of end stage renal disease in the UK and the most common cause in those under 35. Some forms can respond well to treatment if diagnosed early. However, if glomerulonephritis goes unrecognised, it can lead to irreversible loss of renal function. Glomerulonephritis can present in a wide variety of ways, ranging from asymptomatic urinary abnormalities to fulminant disease with life-threatening acute kidney injury and extra-renal manifestations. Asymptomatic invisible haematuria is common. In the absence of infection or a urological cause, glomerulonephritis should be considered. Significant proteinuria (> 1 g/day) in the absence of an identifiable cause warrants referral. 

Kidney stones are common with as many as 1 in 10 people developing a symptomatic stone. Up to 50% of stone formers will have at least one further symptomatic stone in their lifetime. Ureteric colic is unaffected by posture with patients often writhing in seemingly futile attempts to relieve pain. Immediate management comprises effective analgesia while urinalysis is the first step in confirming the diagnosis. One of the challenges facing the GP is to differentiate patients who warrant immediate hospital referral from those who can be seen less acutely.

Both visible (VH) and non-visible haematuria (NVH) may herald serious pathology e.g. malignancy or vasculitis. All patients with VH or symptomatic NVH should have urinalysis, urinary protein estimation (albumin:creatinine or protein:creatinine ratio), and a renal function test. These should also be requested if asymptomatic NVH persists, i.e. in two out of three samples over 6-8 weeks.

Nephrotic syndrome is uncommon in general practice. A GP may only see two or three adult cases in their career. Nephrotic syndrome develops following pathological injury to renal glomeruli. This may be a primary problem, with a disease specific to the kidneys, or secondary to a systemic disorder such as diabetes mellitus. The most common cause in children is minimal change glomerulonephritis. In white adults, nephrotic syndrome is most frequently due to membranous nephropathy whereas in populations of African ancestry the most common cause of nephrotic syndrome is focal segmental glomerulosclerosis (FSGS). Diabetic nephropathy is the most common multisystem disease that can cause nephrotic syndrome. 

The incidence of renal stone disease is increasing globally. In the UK the lifetime risk is estimated to be 8-10%. On a population level, the increase in stone incidence, erosion of gender disparity, and younger age of onset is likely to reflect increasing prevalence of obesity and a Western diet with a high intake of animal protein and salt.

Sertraline is ineffective in patients with chronic kidney disease (CKD) and depression, a randomised controlled trial, from the USA, has found. This study suggests that the prescription of sertraline, and indeed any SSRI, to stage 3b-5 CKD patients with depression can no longer be justified. CBT is probably the best option and there is some evidence of its efficacy in end-stage CKD patients.

Kidney transplantation is the optimum form of renal replacement therapy for suitable patients with end-stage renal disease. A successful transplant represents a much closer approximation to true renal replacement with excretion of waste products, regulation of electrolytes and other substances, than dialysis. The longer a recipient has been dialysis dependent before transplantation the poorer the outcome. Living donor transplantation is associated with better graft and patient survival than transplantation from a deceased donor. A genetic relationship with the recipient is not a prerequisite to becoming a living donor. Having a living donor offers the opportunity of pre-emptive transplant (i.e. avoidance of dialysis altogether).