Proteinuria

Definition:

            It is the urinary excretion of protein more than normal.

Pathophisiology:

            Despite protein retaining properties of glomerular membrane some protein passes into filtrate. In proximal tubule filtered proteins are almost totally reabsorbed. Some large molecular weight proteins get entry into the filtrate by tubular secretion and/or desquamation of tubular epithelial cells, but the amount is negligible. Loss of glomerular integrity and tubular integrity leads to abnormal urinary excretion of protein.

Types of proteinuria:

A. Microproteinuria: It is the condition characterized by increased urinary albumin excretion, but insufficient to be positive on urinary dipstick test.

Causes:

·        Early diabetic nephropathy

·        Hypertension

·        Pre-eclampsia

·        Generalized vascular disease

B. Macroproteinuria: It is the condition characterized by the increased urinary albumin excretion sufficient to be positive on urinary dipstick test. It  is of different types as given below:

·        Benign proteinuria: It is transient and occur following physical activity, fever, trauma, stress.

·        Glomerular proteinuria: It happen due to the loss of glomerular integrity. eg. Glomerulonephritis, nephritic syndrome.

·        Tubular proteinuria: It happen secondary to the loss of tubular integrity. eg. Pyelonephritis, acute tubular nephrits.

·        Overflow proteinuria: It happens secondary to the increased serum protein concentration and increased protein filtration more than the maximum tubular reabsorption capacity. eg. Multiple myeloma.

·        Functional proteinuria:

o   Acute infection and septicemia

o   Leukemia and other hematological disorders

o   Pre-eclampsia

o   Hyperthyroidism

o   Cardiac disease

Consequences of proteinuria:

Ø  Hypoalbuminemia

Ø  Edema

Ø  Hypotonic hypervolemia

Ø  Hypercoagulability and increased risk of thromboembolic phenomenon

Ø  Risk of infection due to loss of immunoglobulin and complement

Ø  Loss of transport protein

Ø  Risk of drug toxicity even at normal dose

Ø  Risk of kernicterus in a jaundice patient

Ø  Hyperlipidemia

Ø  Hypocalcaemia