Dr. med. Dirk Manski

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Proteinuria: Causes and Differential Diagnosis

Definitions of Proteinuria

Proteinuria is the presence of excess serum proteins in the urine.

Normal Protein Excretion:

Protein in the urine should be in the range of 50–150 mg in a 24-hour urine collection.

Functional Proteinuria:

Proteinuria, up to 500 mg/24 h, without the presence of kidney disease is called functional proteinuria. Causes are fever, exercise, orthostasis, exposure to heat and cold, heart insufficiency, or drugs.


Microalbuminuria is the presence of more than 30 mg and up to 300 mg albumin in a 24-h urine collection.

Selective Glomerular Proteinuria:

Selective glomerular proteinuria is the increased excretion of more than 300 mg medium-sized negatively charged proteins such as albumin in a 24-h urine collection.

Non-Selective Glomerular Proteinuria:

Non-selective glomerular proteinuria is the increased excretion of more than 3000 mg proteins of any size in a 24-h urine collection.

Tubular proteinuria:

Tubular proteinuria is the presence of more than 150 mg of small proteins (such as alpha 2-microglobulin) in a 24-h urine collection, while the serum proteins have normal concentrations.

Prerenal Proteinuria:

The increased concentration of small filtered proteins from the plasma leads to overtaxed tubular reabsorption (overflow proteinuria).

Postrenal Proteinuria:

Proteinuria from the upper urinary tract, bladder, prostate, or urethra.

Differential Diagnosis of Proteinuria

Functional Proteinuria:


Microalbuminuria indicates an abnormal leakage of albumin in the renal glomerulus and is a sign of kidney damage:

Selective glomerular proteinuria:

Selective glomerular proteinuria indicates moderate glomerular damage:

Non-selective glomerular proteinuria:

Non-selective glomerular proteinuria indicates severe glomerular damage:

Tubular proteinuria:

Small proteins are in part filtrated in the renal glomerulum and reabsorbed by tubular cells. Tubular proteinuria indicates tubular cell damage:

Prerenal Proteinuria:

Postrenal Proteinuria:

Tumor, urogenital trauma, urinary tract infections, hematuria, semen, vaginal contamination.

Diagnostic Workup of Proteinuria

Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


  Deutsche Version: Differentialdiagnose der Proteinurie