Nephrotic syndrome

Nephrotic syndrome is not a single disease but a pattern that results when the kidney's filtering units (the glomeruli) become very leaky to protein. Normally these filters keep protein in the blood; when they are damaged, large amounts — especially albumin — pour into the urine. This produces a recognisable cluster: very heavy protein loss in the urine (nephrotic-range proteinuria), a low blood albumin, widespread swelling (oedema) as fluid shifts out of the leaky blood vessels, and often a raised cholesterol as the liver reacts to the low albumin. The swelling is typically noticeable around the eyes in the morning and in the legs and ankles, and the urine may look frothy from the protein. The underlying cause varies: in children it is most often a condition called minimal change disease, while in adults it can arise from several specific glomerular diseases, from diabetes, or from conditions like lupus. Nephrotic syndrome also raises the risk of blood clots and infections. Diagnosis rests on the blood and urine tests, and finding the exact cause often needs a kidney biopsy. Treatment targets the underlying cause and the complications, and many people respond well, though the outlook depends heavily on the specific cause.

• Urine protein — very high (nephrotic-range proteinuria); the central finding.
• Albumin (blood) — low, as protein is lost into the urine.
• Urine albumin-creatinine ratio — markedly raised.
• Cholesterol (LDL and total) — often high.
• Creatinine and eGFR — to assess kidney function, which may or may not be affected.
• Additional tests — such as autoimmune markers or a kidney biopsy to find the specific cause.

• Swelling around the eyes, especially in the morning
• Swelling of the legs, ankles and feet
• Frothy or foamy urine
• Weight gain from fluid retention
• Tiredness and loss of appetite
• More frequent infections
• Sometimes symptoms of a blood clot