Special Interest: Renal medicine

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.

Chronic kidney disease (CKD) is defined as either a reduction in measured kidney function (eGFR) or urinary abnormalities (haematuria/proteinuria) or a combination of both, present for more than 3 months. Individuals with newly identified reduced eGFR should have acute kidney injury excluded. All newly identified CKD patients should have blood pressure, dipstick urinalysis, random urine ACR or PCR, glucose, cholesterol and full blood count checked at the earliest opportunity.

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).

About 20% of all adult emergency admissions are affected by acute kidney injury (AKI) and the mortality rate is almost 25%.  It has been estimated that AKI, excluding cases in the community, causes more than 10,000 preventable deaths a year in England. AKI represents a wide spectrum of injury to the kidneys, not just kidney failure, the vast majority of AKI cases start with an illness in the community. In AKI, loss of kidney function contributes to morbidity and mortality. Patients die from AKI rather than with AKI as a complication of an underlying illness. The definition of AKI now includes any adult with ≥ 26 µmol/L rise in creatinine from baseline over 48 hours or less, or  ≥ 50% rise in creatinine from baseline known or presumed to have occurred over seven days or less.