subnephrotic

Subnephrotic refers to a level of urinary protein excretion that is below the threshold for nephrotic-range proteinuria. In adults, this is typically defined as protein loss less than about 3.5 grams per day, or a spot urine protein-to-creatinine ratio well below 3500 mg/g. Subnephrotic proteinuria indicates glomerular injury that is present but not yet sufficient to meet nephrotic criteria, and it may be asymptomatic or accompanied by mild edema in some cases.

Evaluation of subnephrotic proteinuria usually begins with repeat urinalysis and quantification of protein excretion, using a 24-hour urine collection or a spot urine protein-to-creatinine ratio. Basic metabolic panels assess renal function, electrolytes, and albumin, while lipid profiles and blood pressure measurements help characterize associated metabolic conditions. The evaluation aims to identify an underlying cause, monitor progression, and exclude nephrotic-range disease.

Common etiologies include early diabetic nephropathy, hypertensive or ischemic nephrosclerosis, mild glomerulonephritis, and other conditions causing limited glomerular permeability to protein. Subnephrotic proteinuria can also be transient, related to fever, exercise, dehydration, or urinary tract infections; persistence beyond several months warrants formal nephrology assessment.

Management focuses on treating the underlying cause, controlling blood pressure (often with ACE inhibitors or ARBs, which can reduce proteinuria), and addressing modifiable risk factors such as glycemic control in diabetes and lipid management. Regular monitoring of kidney function and proteinuria helps guide therapy and assess prognosis. Overall, subnephrotic proteinuria has a variable prognosis depending on etiology and comorbidities, and may progress to nephrotic-range disease in some cases.