Renal medicine - Special interest

Diabetic kidney disease is associated with a very high risk of cardiovascular disease (CVD) and premature mortality from cardiovascular events. There is good evidence that multifactorial interventions that optimise BP, limit proteinuria and minimise cardiovascular risk can reduce morbidity and premature mortality. Early diabetic kidney disease is asymptomatic. Microalbuminuria, defined as a urinary ACR of 3-30 mg/mmol on two occasions three months apart is the earliest clinically detectable indicator of diabetic kidney disease. Excellent glycaemic control can delay onset of microalbuminuria.

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. 

End stage renal disease can be defined as the requirement for kidney transplantation or dialysis therapy. In the UK in 2016, of the 63,162 people receiving renal replacement therapy 53% were renal transplant recipients, 41% were on haemodialysis and 6% were on peritoneal dialysis. Dialysis should be started when: symptoms of uraemia impact on day to day living; the need is indicated by biochemical measures or uncontrollable fluid overload or at an eGFR of 5-7 ml/min/1.73 m² in the absence of symptoms. The choice of dialysis modality is influenced by the individual’s functional status, social circumstances and confidence.

Renal cell carcinoma should be suspected in the presence of: localising symptoms such as flank pain, a loin mass or haematuria; constitutional upset including weight loss, pyrexia and/or night sweats; or unexplained test results. Smoking, obesity and hypertension are common risk factors and all three demonstrate a dose-response relationship with the relative risk of renal cell carcinoma.

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. 

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).