What Is Orthostatic Proteinuria?

(Orthostatic proteinuria) Orthostatic proteinuria refers to urine protein negative when lying down and positive when walking upright or standing. The total excretion within 24 hours does not exceed 1.5 grams, but it can also be very high. Upright tests are commonly used clinically to induce and detect such proteinuria.

Orthostatic proteinuria

Orthostatic proteinuria

Orthostatic proteinuria is a type of physiological or functional proteinuria, which refers to proteinuria that occurs when the patient is in an upright position or an anterior lobe, and disappears when lying. It is usually seen in children and adolescence, and its incidence is about 2% to 10%.

The diagnosis of this disease should have the following conditions: no history of kidney disease and clinical manifestations; no other systemic diseases related to kidney disease; no hypertension; no abnormal urine sediment; normal renal function; blood biochemistry and serum The examination is normal; the urinary tract X-ray examination is normal; 24-hour urine protein is generally less than lg, even up to 2-3g, but the total amount of urine protein in the supine position for 12 hours should be less than 75mg.

The specific mechanism of orthostatic proteinuria is not fully understood, and may be:

In the upright position, the lordosis of the spine, the rotation of the liver forward and downward, oppress the inferior vena cava, increase the renal vein pressure, cause renal congestion, and increase the hydrostatic pressure of the glomerular capillaries to produce proteinuria.

Increased renal blood flow leads to an increase in the total amount of protein flowing through the nephron, resulting in an increase in the total amount of protein in the final urine. When renal blood flow returns to normal, proteinuria disappears. Common causes include: cold, strenuous exercise, tension, sympathetic nerve excitement, application of vasoactive drugs, and so on.

Some people find that applying a tourniquet to ligate the extremities can cause proteinuria, and the proteinuria disappears after the tourniquet is loosened; when standing upright in cold water to shrink the surrounding blood vessels, it can prevent the production of urine protein, while standing in hot water and surrounding blood vessels to expand , It can make urine protein worse; children with orthostatic proteinuria often have orthostatic hypotension and emotional instability.

It is speculated that orthostatic proteinuria may also be caused by the reduction of blood flow in the abdominal cavity, increased sympathetic nerve tension, increased catecholamine secretion, increased renin-angiotensin activity, and increased renal vasoconstriction when lying or standing. ^[1]

This type of proteinuria occurs mostly in lean and healthy adolescents, and most orthostatic proteinuria is benign. If you have been diagnosed with orthostatic proteinuria after an internal or pediatric examination, you don't need to worry about it, because the disease will naturally heal after adulthood, and your life and diet need not be restricted. Of course, for some patients with repetitive orthostatic proteinuria, often accompanied by hematuria, cast urine or other clinical manifestations, close and careful observation should be given to the possibility of nephropathy.