Urine examination – Leukocytes, Nitrites, Hemoglobin…

The urinalysis is used as a complementary diagnostic method since the second century. It is a painless examination, simple collection and fast result, which makes it much less painful than blood tests, which can only be collected through needles.

Urinalysis may give us important clues about diseases, especially kidney and urinary problems. The presence of blood, pus (pus), proteins, glucose, and various other substances in the urine is often an important hint for diseases that may not yet have very clear signs or symptoms.

The fact that urine looks completely normal does not mean that it can not contain changes. Even the presence of blood may be only microscopic, and it is not possible to identify it by any means other than by laboratory examination of the urine.

Urine can also be used to research the presence of drugs in the body, whether licit or illicit. However, for this type of research, special tests need to be requested. A simple urine test, called EAS or Urine type 1, is not intended to make drug or drug tests.

The three most common urine tests are:

1- EAS (abnormal sediment elements) or urine type 1 *
2- 24-HOUR URINE
3- UROCULTURE

* In Portugal, EAS is called Urine 2.

In this article we will address only the simple urine test, also known as EAS, urine type I or urine type II.

The information contained herein is intended to assist in understanding the results of urinalysis. In no way should the patient use this text to interpret exams without the advice of a physician. The presence of leukocytes in the urine, altered pH, description of epithelial cells, the presence of mucus, or any other findings in ESA should always be correlated with the patient’s clinical history, symptoms and physical examination.

OTHER ARTICLES ON URINE:
– 24-HOUR URINE | How to harvest and what it is for
– UROCULTURE EXAM | INDICATIONS AND HOW TO COLLECT
– URINE COLOR (URINE GREEN, PURPLE, ORANGE, BLUE)

EAS OR URINE TYPE I

EAS is the simplest urine test done by collecting 40-50 ml of urine in a small plastic pot. We usually request that the first morning urine be used, neglecting the first jet. This small amount of unneeded urine serves to eliminate impurities that may be in the urethra (urinary tract that carries urine from the bladder). After the first jet is eliminated, the container is filled with the rest of the urine.

The first morning urine is the most commonly used, but it is not mandatory. Urine can be collected at any time of the day.

The urine sample should ideally be taken from the laboratory itself, because the fresher it is, the more reliable its results. An interval of more than two hours between collection and evaluation may invalidate the result, especially if the urine has not been kept under refrigeration.

The EAS is divided into two parts. The first is done through chemical reactions and the second by visualizing drops of urine through the microscope.

In the first part a tape is dug in the urine, called dipstick, as in the photo of the beginning of the text. Each ribbon has several colored squares made up of chemicals that react with certain elements of the urine. This part is so simple that it can be done in the doctor’s office itself. After 1 minute, compare to the colors of the squares with a reference table that usually comes in the packaging of the EAS tapes themselves.

Through these reactions and with the complement of microscopic examination, we can detect the presence and amount of the following urine data:

– Density.
– pH.
– Glucose.
– Proteins.
– Blood cells.
– Leukocytes .
– Ketones.
– Urobilinogen and bilirubin.
– Nitrite.
– Crystals.
– Epithelial cells and cylinders.

The results of the dipstick are qualitative and not quantitative, that is, the tape identifies the presence of these substances mentioned above, but the quantification is only approximate. The result is usually given in a cross-graduation of 1 to 4. For example: a urine with “4+ proteins” has a large amount of protein; A urine with “1+ proteins” has a small amount of protein. When the concentration is very small, some laboratories provide the result as “traces of proteins”.

Let us then go to the EAS reference values:

• Density:

The density of pure water equals 1000. The nearer this value, the more diluted the urine is. Normal values range from 1005 to 1035. Urines with a density close to 1005 are well diluted; Near 1035 are very concentrated, indicating dehydration. Urines with a density close to 1035 tend to be very yellowish and usually have strong odor (read: URINE WITH STRONG SMELL AND SMELLY SMELL ).

The density indicates the concentration of solid substances diluted in the urine, mostly mineral salts. The less water in the urine, the greater its density.

• pH:

Urine is naturally acidic, since the kidney is the main means of eliminating the body’s acids. While the pH of the blood is usually around 7.4, the pH of the urine ranges from 5.5 to 7.0, that is, much more acidic.

PH values greater than or equal to 7 may indicate the presence of bacteria that alkalize urine. Other factors that may leave the urine more alkaline are a diet low in animal protein, a diet rich in citrus fruits or milk derivatives, and use of medications such as acetazolamide, potassium citrate or sodium bicarbonate. Having vomiting hours before the exam can also be a cause of more alkaline urine. In rare cases, some diseases of the renal tubules can also leave urine with pH above 7.0.

Values less than 5.5 may indicate acidosis in the blood or disease in the renal tubules. A diet with high animal protein load can also cause more acidic urine. Other conditions that increase urine acidity include episodes of diarrhea or use of a diuretic such as hydrochlorothiazide or chlorthalidone.

The most common value is a pH around 5.5-6.5, but even values above or below those described may not necessarily indicate some disease. This result should be interpreted by your doctor.

• Glucose:

All glucose that is filtered into the kidneys is reabsorbed back into the blood through the renal tubules. Thus, it is not normal to present evidence of glucose in the urine.

The presence of glucose in the urine is a strong indication that blood levels are high. It is very common for people with diabetes mellitus to have glucose loss through the urine. This is because the amount of sugar in the blood is so high that part of it ends up coming out of the urine. When blood glucose levels are above 180 mg / dl, there is usually loss in urine (read: DIAGNOSIS AND DIABETES MELLITUS SYMPTOMS ).

The presence of glucose in the urine without the individual having diabetes is usually a sign of kidney tubule disease. This means that although there is no excess glucose in the urine, the kidneys can not prevent their loss.

Basically, the presence of glucose in the urine indicates excess blood glucose or kidney disease.

• Proteins:

Most of the proteins circulating in the blood are too large to be filtered by the kidney, so in normal situations we do not usually see proteins present in the urine. In fact, there may even be small amounts of protein in the urine, but they are so few that they are not usually detected by the tape test. Therefore, normal urine has no protein.

Small amounts of protein in the urine can be caused by dozens of situations, ranging from benign and trivial situations such as the presence of fever, physical exercise hours before urine collection, dehydration or emotional stress, to more serious causes such as urinary tract infection , Lupus, renal glomeruloneal diseases, and renal damage from diabetes.

READ ALSO:
– NEFRÓTICA SYNDROME | Causes, Symptoms and Treatment
– FOAMING URINE AND PROTEINURIA
– WHAT IS A GLOMERULONEFRITE?

Large amounts of protein in the urine, on the other hand, almost always indicate the presence of a kidney disease, usually diseases of the renal glomeruli, which are the microscopic structures responsible for the filtration of blood.

There are two ways of presenting the result of proteins in the urine: in crosses or through an estimate in mg / dL:

Absence = less than 10 mg / dL (normal value)
Traces = between 10 and 30 mg / dL
1+ = 30 mg / dl
2+ = 40 to 100 mg / dL
3+ = 150 to 350 mg / dL
4+ = Than 500 mg / dL

The presence of proteins in the urine is called proteinuria and should always be investigated. The 24-hour urine test is usually done to accurately quantify the amount of protein that is being lost in the urine (read: URINE 24 HOURS How to Scoop and What It Serves ).

• Blood in the urine – Hemoglobin in the urine – Blood in the urine:

As with proteins, the amount of red blood cells in the urine is negligible and can not be detected by examination of the tape. Once again, the results are usually provided in crosses. The normal thing is to have no red blood cells (hemoglobin).

Since red blood cells are cells, they can be seen with a microscope. Thus, in addition to the tape test, we can also search for red cells directly by microscopic examination, a technique called sedimentation. Through the microscope it is possible to detect any presence of blood, even minimal amounts not detected by the tape.

In this case, normal values are described in two ways:
– Less than 3 to 5 RBCs per field or less than 10,000 cells per mL

The presence of blood in the urine is called hematuria and can occur from a variety of diseases, such as infections, kidney stones, and severe kidney disease (for more details on hematuria, read: HEMATURIA (URINE WITH BLOOD) ).

A false positive result can occur in women who collect urine while they are in the menstrual period. In this case, the blood detected does not come from the urine, but from the still residual blood present in the vagina. In men, the presence of semen in urine may also cause false positive.

Once hematuria is detected, the next step is to evaluate the shape of the red blood cells in an examination called “erythrocyte dysmorphism”. Dysmorphic RBCs are erythrocytes with abnormal morphology, common in some diseases such as glomerulonephritis (read: WHAT IS A GLOMERULONEFRITE? ). Small amounts of dysmorphic erythrocytes may be present in the urine without clinical relevance. Only values above 40-50{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} are considered to be relevant.

It is not every laboratory that has people qualified to perform this exam. Therefore, it is often not done automatically. It is necessary for the doctor to request this evaluation specifically.

• Leukocytes or pyocytes – Leukocyte

The white blood cells , also called pus cells, are white blood cells, our immune cells. The presence of leukocytes in the urine usually indicates that there is some inflammation in the urinary tract. It usually suggests a urinary tract infection, but may be present in a number of other situations, such as trauma, use of irritants, or any other inflammation not caused by an infectious agent. We can simplify and say that leukocytes in the urine means pus in the urine.

Because they are also cells, leukocytes can be counted in the sediment. Normal values are below 10,000 cells per ml or 5 cells per field

Some dipsticks have a square for detection of leukocytes , usually the result is described as “leukocyte esterase”. The normal thing is to be negative.

• Ketones or ketone bodies:

Ketone bodies are products of the metabolism of fats. Ketone bodies are produced when the body is having difficulty using glucose as a source of energy. The most common causes are diabetes, prolonged fasting and strict diets. Other less common conditions include fever, acute illness, hyperthyroidism, pregnancy and even breastfeeding.

Normally the production of ketones is very low and these are not present in the urine.

Some medicines like captopril, valproic acid, vitamin C (ascorbic acid) and levodopa can cause false positives.

• Urobilinogen and bilirubin

Also usually absent in the urine, they may indicate liver disease (liver) or hemolysis (abnormal destruction of the red blood cells). Bilirubin only usually appears in the urine when your blood levels exceed 1.5 mg / dL. Urobilinogen may be present in small amounts without this being clinically relevant.

• Nitrites

Urine is rich in nitrates. The presence of bacteria in the urine turns these nitrates into nitrites . Therefore, tape with positive nitrite is an indirect sign of the presence of bacteria. Not all bacteria have the ability to metabolize nitrate, so urine test with negative nitrite in no way discards urinary tract infection.

In fact, EAS only suggests infection. The presence of red blood cells, associated with positive leukocytes and nitrites , speaks a lot in favor of urinary infection, but the test of certainty is uroculture (read: EXAME UROCULTURA | Indications and how to harvest ).

The nitrite research is done by the Griess reaction, which is the name given to the nitrite reaction with an acidic medium. Therefore, some laboratories provide the result as Griess positive or Griess negative, which is equal to positive nitrite or negative nitrite, respectively.

• Crystals

This is perhaps the most misinterpreted result, both by patients and by some physicians. The presence of crystals in the urine, especially of calcium oxalate, calcium phosphate or amorphous urates, has no clinical significance. Contrary to what may be imagined, the presence of crystals does not indicate a greater propensity to form kidney stones. That being said, it is important to note that in some cases the presence of certain crystals may be a sign of some disease.

The crystals with clinical relevance are:

  • Cystine crystals – Indicate a disease called cystinuria.
  • Magnesium-ammonium-phosphate crystals (called struvite crystals or triple phosphate crystals) may be normal but may also be present in cases of very alkaline urine caused by urinary infection by the bacteria Proteus or Klebsiella . Patients with kidney stones due to struvite stones usually have these crystals in the urine.
  • Tyrosine Crystals – Gifts in a disease called tyrosinemia.
  • Bilirubin Crystals – Usually show Liver Disease.
  • Cholesterol Crystals – It is usually a sign of massive protein losses in the urine.

The presence of uric acid crystals, in large numbers, should also be valued, as they can occur in patients with gout or neoplasias, such as lymphoma or leukemia. Small amounts of uric acid crystals, however, are common and do not indicate any problems.

• Epithelial cells and cylinders

The presence of epithelial cells in the urine is normal. It is the urinary tract cells themselves that shed. They are only valuable when they are grouped in cylinder form, called epithelial cylinders.

Because the renal tubules are cylindrical, every time we have some substance (proteins, cells, blood …) in large quantities in the urine, they are grouped into a cylinder. The presence of cylinders indicates that this substance came from the renal tubules and not from other points of the urinary tract such as the bladder, ureter, prostate, etc. This is very relevant, for example, in cases of bleeding, where a blood cylinder indicates the glomerulus as the origin, not the bladder, for example.

The cylinders that may indicate some problem are:

– Hematologic (blood) cylinders = Indicate glomerulonephritis.
– Leukocyte Cylinders = Indicate inflammation of the kidneys.
– Epithelial cylinders = indicate lesion of the tubules.
– Fatty cylinders = indicate proteinuria.

Hyaline cylinders do not indicate disease, but can be a sign of dehydration.

The presence of mucus in the urine is non-specific and usually occurs by the accumulation of epithelial cells with crystals and leukocytes . It has very little clinical utility. It’s more an observation.

Regarding EAS (urine type I) it is important to note that this is an analysis that must always be interpreted. False positives and negatives are very common and you can not close any diagnoses just by comparing the results with the reference values.

• Ascorbic acid in urine

It is common for laboratories to draw attention when there is ascorbic acid (vitamin C) in the urine. This is important because ascorbic acid can alter dipstick results, especially in the detection of hemoglobin, glucose, nitrites , bilirubin, and ketones. It is important for your doctor to know that unexpected results may be false positives or false negatives caused by vitamin C.

• Example of normal EAS (urine type I)

By way of example only, the following is a model of how laboratories present the results of the urine summary examination. This test is normal.

COLOR – citrus yellow
APPEARANCE – clear
DENSITY – 1,015 (normal ranges from 1005 to 1030)
PH – 5,0 (normal ranges from 5.5 to 7.5)

CHEMICAL EXAMINATION

Glucose – absent
Proteins – absent
Ketone – absent
Bilirubin – absent
Urobilinogen – absent
Leukocytes – absent
Hemoglobin – absent
Nitrite – negative

SEDIMENT MICROSCOPY (sedimentation)

Epithelial cells – some
Leukocytes – 5 per field
Blood cells – 3 per field
Muco – absent
Bacteria – absent
Crystals – absent
Cylinders – absent