Crystalluria is the presence of various crystalline inclusions in the urine. It can occur both in healthy people and be a sign of a serious illness. Diagnostic value is the type of crystals, their number, as well as repeated detection during repeated studies. Some crystals can change the color of urine. Prolonged crystalluria is considered one of the main risk factors for the development of urolithiasis. Crystalluria is detected by microscopic examination of the urinary sediment in a general urinalysis. Correction is carried out as part of the treatment of the underlying disease.
There are several types of crystals:
Almost all types of urinary crystals can be detected in a small amount in a random urine sample from any healthy person. It is worth suspecting any disease or pathological condition only if they are constantly present and in large quantities. The exception is crystals of cholesterol, amino acids and bilirubin, the detection of which always indicates the presence of pathology.
The most common salts in urine are oxalates. Normally, about 3 mg of oxalates are excreted in the dissolved state in the urine per day. They begin to crystallize when urine is left at room temperature for a long time. They have the form of colorless octahedrons, in appearance resembling postal envelopes or pyramids. There are also oval-shaped oxalates, in the form of an hourglass, gymnastic weights.
It is sometimes difficult to differentiate between ovoid oxalates and erythrocytes by morphology. To do this, a drop of acetic acid is added to the urine sediment, which causes lysis of red blood cells. In parenchymal or obstructive jaundice, ovoid oxalates are stained yellow or dark yellow by bilirubin, while oxalates in the form of octahedrons remain colorless. Spherical oxalates, similar to drops of fat, are found in patients with chronic glomerulonephritis.
There are primary and secondary crystalluria. Primary oxalaturia (oxalosis) is a genetically determined metabolic disorder in which oxalates are deposited in the internal organs, their excretion in the urine increases, which contributes to the rapid development of oxalate-calcium urolithiasis.
Secondary oxalaturia can have many causes:
crystalluria
On the 2nd place in the frequency of occurrence is urate crystalluria. In large quantities, uric acid crystals stain the urine brick red. Most often, urates are diamond-shaped, yellow or brownish in color, sometimes colorless. When taking acetylsalicylic acid, they can turn gray-violet or black. In some cases, urates have a pronounced polymorphism - they can be presented in the form of a barrel, grindstone, spindle.
Sometimes they resemble crystals of cholesterol, cystine, erythrocytes, which makes it difficult to identify them. In differential diagnosis, the ability of urates to dissolve in sodium and potassium hydroxide, as well as information about the environment of urine (should be acidic), helps. This type of crystalluria can be found in a healthy person, whose diet is represented mainly by meat food.
Prolonged uraturia indicates a high concentration of uric acid in the blood (hyperuricemia) due to its increased formation. Uraturia can be observed in the following pathologies:
There are 4 main types of crystals of salts of phosphoric acid - amorphous phosphates, neutral magnesium phosphate, neutral calcium phosphate, tripel phosphates. The most common cause of phosphaturia is the consumption of dairy products, as well as a large amount of plant foods, which contribute to a shift in the pH of urine to the alkaline side. Other etiological factors:
The synonymous name is phosphate lands. Under a microscope, they look like colorless amorphous masses, consisting of small balls and grains, grouped into piles of various sizes. Their presence in the urine often causes it to become cloudy, and after centrifugation, a white precipitate resembling a leukocyte precipitate forms at the bottom of the tube.
A synonym is ammonia-magnesium phosphate. They are transparent, colorless crystals resembling coffin lids. If the patient has a pathology of the liver or biliary tract, with prolonged standing of urine, tripelphosphates are stained yellow with bilirubin.
Synonym - neutral magnesium phosphate. Crystals can have a different shape - oblong plates with strong light refraction, a trapezoid, a flat plate.
Another name is neutral phosphate lime. The crystals are colorless prisms with pointed ends. They can be located in isolation or grouped, forming sockets. Sometimes they look like plates or bundles of needles resembling tyrosine.
Calcium carbonate in the urine is rare. Salts look like small balls stuck together, folding into figures of drumsticks or gymnastic weights. Often combined with tripelphosphates and amorphous phosphates. They are better visualized after the urine has been in room conditions for a long time. Calcium carbonate can be seen in the urine of a person who eats a lot of plant foods.
A healthy person excretes a small amount of hippuric acid in the urine. An increase in its concentration with subsequent crystallization can occur with the use of fruits and fruit berries (lingonberries, plums, pears), benzoic and salicylic acids. Hippururia is also characteristic of putrefactive colitis, diseases of the liver, gallbladder. Hippuric acid has the appearance of colorless rhombic tablets with beveled ends.
Bilirubin is a bile pigment, it is excreted in the urine in minimal amounts. With an increase in the concentration of direct bilirubin in the urine, it crystallizes. This is observed when liver cells are damaged (alcoholic or viral hepatitis, cirrhosis) or in violation of the outflow of bile (cholecystitis, cholelithiasis, primary sclerosing cholangitis).
Bilirubin crystals can also be found in diseases accompanied by proteinuria (glomerulonephritis, nephropathy in autoimmune pathologies or hemoblastoses). This is due to the fact that with a damaged glomerular apparatus of the kidneys, indirect bilirubin is able to enter the urine, which is not normally observed. Microscopically, bilirubin is presented in the form of yellowish-brown granules or needles collected in bundles. They are often superimposed on leukocytes, squamous, transitional epithelial cells.
When crystallized in the urine, cholesterol takes the form of very thin diamond-shaped plates that overlap each other. Often, together with them, it is possible to identify drops of fat, cells of the renal epithelium in a state of fatty degeneration, hyaline cylinders with fatty overlays. Reasons for detecting cholesterol in urine:
Cystine crystals are hexagonal thin plates of regular or irregular shape. For the purpose of differential diagnosis, a test for cystine is used - 5% sodium cyanide and 5% sodium nitroprusside are added to the urine. A purple-red color indicates the presence of cystine. There are 2 clinical forms of hereditary disorders of cystine metabolism:
There is also secondary or acquired cystinuria. Her reasons are as follows:
Normally, these amino acids are excreted in the urine in small amounts. Their crystallization occurs with increasing concentration. Leucine is represented by matte-shiny balls of various sizes with concentric striation, located in isolation or in clusters. Tyrosine has the appearance of thin, small needles grouped into bundles or stars.
Crystalluria of these amino acids are observed in genetic metabolic disorders or extensive tissue and cellular decay:
Detection of crystals of drugs in the urine is often found with their long-term use or overdose. The formation of drug crystals can lead to blockage of the renal tubules and cause acute kidney injury. Basically, LS crystals have the form of thin needles or small rectangles. Most often, drug crystalluria develops against the background of taking:
Urates under the microscope
Despite the fact that crystals are quite common in normal urine, the re-detection of crystalluria requires a visit to a general practitioner to determine the cause. During the interview, the patient clarifies the nature of the person’s nutrition, what medications he takes, whether he is registered with the dispensary. An additional examination is scheduled, including:
In the vast majority of cases, dietary recommendations are sufficient for the disappearance of crystalluria - drinking plenty of water, a balanced diet of plant and animal foods. Patients with hereditary hyperoxaluria are prohibited from taking foods rich in oxalic and ascorbic acids. People with amino acid metabolism disorders are prescribed a strict diet with the maximum possible restriction of tyrosine, leucine, tryptophan.
With drug crystalluria, drug withdrawal or a decrease in its dosage is required. Conservative therapy of crystalluria directly depends on the cause:
Patients with urolithiasis, depending on the size of stones, their shape, localization, are shown various methods of removal - shock wave lithotripsy (destruction by directed ultrasound), laparoscopic or open surgery. In cholelithiasis, laparoscopic cholecystectomy is performed.
The presence of crystalluria alone makes it difficult to assess the prognosis for a patient. The exception is rare crystals of amino acids, the presence of which indicates a severe genetic disease. The outcome is determined by the underlying pathology, however, in most cases, the presence of crystalluria does not imply any disease.