Explanation

Erythrocytes and free hemoglobin: what is measured?

The pad reacts to hemoglobin, the red pigment in red blood cells (erythrocytes). It detects both whole red blood cells and free hemoglobin, which is released when red blood cells break apart. Myoglobin, a protein from muscles, also gives a positive reaction. The dipstick detects blood even in amounts that are not visible to the naked eye (non-visible hematuria).

What can it detect?

A bladder infection or kidney infection (pyelonephritis)
Kidney stones
Kidney damage or inflammation of the kidney filters
Rarely: a tumor in the bladder or kidney, especially at older age

Result

What does the result mean?

Positive result

A positive result is often caused by menstrual blood, heavy exercise such as running, a bladder infection, kidney stones or sex shortly before collection. After muscle damage from extreme exercise, myoglobin can give a positive result without red blood cells. If blood keeps being found in the urine on repeat testing without an infection, this can fit a kidney disease, especially if there is also protein in the urine or blood pressure is high, or an enlarged prostate. Rarely: a tumor in the bladder or kidney; this chance increases with age and with smoking.

Negative result

A negative result is normal. Vitamin C can suppress the reaction and give a false negative result. Red urine with a negative dipstick is usually caused by food, such as beets, or by medicines.

After an abnormal result

With a positive result, the GP repeats the dipstick outside menstruation and without heavy exercise beforehand, and rules out an infection with a urine test. With a persistently positive result, microscopic examination of the urine (sediment), the albumin-creatinine ratio, the eGFR and a blood pressure measurement follow. Depending on age, risk factors and results, the GP refers you to a urologist or an internist-nephrologist.

Reliability

How reliable is the test?

A urine dipstick is a quick screening and not a diagnosis. According to the Dutch GP guideline (NHG) on urinary tract infections, the dipstick is a first step with symptoms that fit a bladder infection; if in doubt, a culture or sediment test follows. For detecting kidney damage, the dipstick is less sensitive than the albumin-creatinine ratio in urine and the eGFR in blood; the NHG guideline on chronic kidney damage is based on those. In people without symptoms, most abnormal dipstick results are temporary or harmless; a single abnormal result therefore says little.

What can affect the result?

Sample collection: preferably use first morning urine or urine that has been in the bladder for at least 4 hours, and after washing, catch the middle part of the stream (midstream), so that no discharge or skin bacteria get into it.
Menstruation, and the days before and after it, often gives a positive result for blood and sometimes for leukocytes and protein; it is better to collect at another time.
Vitamin C (supplements or a lot of fruit juice) can suppress the reaction for blood, glucose, nitrite and bilirubin and give a false negative result.
Heavy exercise, fever and dehydration in the day before sample collection can temporarily cause protein, blood or ketones. Urine that has been standing for a long time or has become warm gives less reliable results, especially for nitrite, bilirubin, urobilinogen and pH.

Preparation

Preferably use the first morning urine, or urine that has been in your bladder for at least 4 hours.
Collect the middle part of the stream.
Do not collect urine during your period.

Who it is for

Who is the test useful for?

Useful for

Useful with symptoms that may fit a bladder infection, such as frequent and painful urination, or as a simple addition to blood tests for the kidneys, sugar or liver. For detecting kidney damage in diabetes or high blood pressure, the albumin-creatinine ratio in urine says more than the dipstick. In people without symptoms and without risk factors, the chance of a harmless abnormality is greater than the chance of a real condition.

How common is it?

Bladder infection is one of the most common infections in women; in men it is much less common. Chronic kidney damage occurs in about 1 in 10 adults, usually without symptoms. In people without symptoms, an abnormality on the dipstick is found in some, usually without a serious cause.

NHG guideline on urinary tract infections; NHG guideline on chronic kidney damage

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