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Today's laboratory exercise focuses on diagnostic urinalysis, a vital tool in assessing the health of the endocrine system, kidneys, and urinary tract. Urine serves as a reflection of the various chemical components present in the blood. For this lab, artificial urine samples are used. The primary test conducted in this lab is the "dipstick" urinalysis, wherein students analyze the chemical composition of urine by immersing a chemical indicator stick into a urine sample. The chemicals in the indicator stick's pad react with various biochemicals, ions, and salts found in urine, providing indications of the presence of hemoglobin, glucose, ketones, protein, and specific gravity.
Changes in color on the dipstick indicate the quantity and presence of specific urine components, offering insights into potential health issues. For example, high levels of glucose suggest an inability of the endocrine system to regulate sugar concentration, while dilute urine may indicate adrenal gland defects affecting kidney function. Urine containing blood and protein can indicate damage to the kidney's blood-filtering system.
No hypothesis is necessary as this lab is an observational labю
The objectives of this lab include:
Calibration is crucial to ensure the accuracy of data collected from patient samples. The use of positive and negative standard solutions is essential for this purpose. A false positive result, when using water, may indicate that the "stick" is detecting substances not present in the sample, while a false negative result suggests the stick's inability to detect substances present in the sample.
This laboratory exercise introduced the concept of urinalysis, a diagnostic test that plays a crucial role in evaluating the health of the endocrine system, kidneys, and urinary tract. Urine can be visually examined for color (ranging from clear to dark yellow or red) and clarity (ranging from clear to cloudy), as well as odor. A comprehensive diagnostic urinalysis encompasses both dipstick evaluation and microscopic analysis.
The dipstick evaluation involves various parameters, including glucose, ketones, pH, protein, blood, bilirubin, among others. Microscopic analysis allows for the detection of specific elements such as bacteria (indicative of urinary tract infections), red blood cells (RBCs), crystals (associated with metabolic derangements), renal tubular cells (a sign of toxicity or severe renal disease), and transitional cells (originating from the bladder). It's important to note that urine acidity (acid urine) and alkalinity (alkaline urine) can result in the formation of crystals that differ from those found in normal urine.
During the lab, students learned various terms and concepts, including:
To ensure the accuracy of diagnostic tests and equipment used for these determinations, calibration is performed. Calibration helps prevent false negatives and false positives. A false positive result, when using water, suggests that the "stick" is detecting substances that are not present, while a false negative result indicates that the stick is unable to detect substances that are actually present in the sample.
In conclusion, students successfully conducted a urinalysis dipstick test. The lab involved testing both negative and positive standard solutions before analyzing the urine samples from Jane and John. Based on the results, it was determined that:
Through this lab, students gained insight into different diseases and health issues associated with the dipstick test results. This experience provided valuable hands-on learning about the diagnostic potential of urinalysis.
1. What are the possible causes of John’s test results?
John’s urine was clear and tested negative for protein, which indicated it was normal. The pee was slightly turbid which could be caused by Lipiduria, hyperoxaluria, chyluria, pyuria, excess phosphate crystals precipitating in alkaline urine, hyperuricosuria, or contamination with vaginal mucus or epithelial cells. The urine had a strong odor which could indicate alkaline fermentation, diabetic ketoacidosis, cysteine decomposition, gastrointestinal-bladder fistulae, or could be caused by medications or diet. John’s urine was observed to have a specific gravity of 1.005, which is lower than normal urine. Decreased specific gravity is seen in excessive fluid intake, renal failure, pyelonephritis, and central and nephrogenic diabetes insipidus. False low readings of specific gravity are associated with alkaline urine (a high-citrate diet).
The pH of John’s pee is 5, which is considered to be within the normal range, but it is on the lower end which could be caused by diet and uric acid calculi. The glucose was extremely high with 1000mg, which is extremely strange due to that fact that nearly all glucose filtered by the glomeruli is reabsorbed in the proximal tubules and only undetectable amounts appear in urine in healthy patients. False positive results are seen when high levels of ketones are present and also in patient taking levodopa.
Something to remember about dipstick tests is that reagent strip tests are specific for glucose. John’s sample tested with small (+) amounts of ketones. A positive test, since ketones are not normally found in urine, is associated with uncontrolled diabetes, pregnancy without diabetes, carbohydrate-free diets, and starvation. False trace results may be seen in highly pigmented urine and in patiens taking levodopa. John’s urine also showed trace amounts of blood.
2. Of the diseases mentioned, what disease might John have?
Of the diseases mentioned, it is believed that John might have either diabetes mellitus or a renal impairment.
3. How did you come to this conclusion about John’s condition?
The conclusion was made that John might have diabetes mellitus, due to the high levels of glucose, slightly lower pH, and traces of ketones. The decreased level of specific gravity, and traces of blood lead to the belief that John may have a renal impairment.
4. What are the possible causes of Jane’s test results?
Jane’s urine was a very light yellow with a very faint odor, tested negative for ketones, tested negative for proteins, had a pH of 6, and had a specific gravity of 1.015. All of these characteristics do not indicate abnormalities with Jane’s pee. The glucose was extremely high with 1000mg. False positive results are seen when high levels of ketones are present and also in patient taking levodopa.
Something to remember about dipstick tests is that reagent strip tests are specific for glucose. Jane also showed About 250 Ery/nanoliters of blood in her urine. This could indicate lower urinary tract bleeding and inflammation/infection, acute glomerulonephritis, or lupus nephritis. The protein portion of the dipstick tested for 100 (++) in Jane’s urine sample. Proteinuria is indicative of renal disease, and small amounts accompany hematuria and acute urinary tract infection.
5. Of the diseases mentioned, what disease might Jane have?
Of the diseases mentioned, Jane might have an acute urinary tract infection/inflammation, or renal disease.
6. How did you come to this conclusion about Jane’s condition?
The conclusion about renal disease is because proteinuria is indicative of renal disease. Jane might instead have an acute urinary tract infection/inflammation due to not only the protein in her urine but also the blood in the urine.
7. Why is Urine useful as an indicator of the endocrine and kidney disease?
Urine is as an indicator of the endocrine and kidney disease because through its protein, pH, glucose, ketones, specific gravity, and blood that can possibly be found, physicians can diagnose disease. Urine indicates diseases with the kidney because the kidney is what filters out the body fluids that become the urine.
8. What is the laboratory procedure that can be used to test the presence of certain specific biochemicals in urine?
The laboratory procedures that can be used to test the presence of certain specific biochemical in urine could be microscopic analysis, or even a urine electrophoresis test
9. Which blood chemical will be found in high levels in patients diagnosed with untreated diabetes mellitus?
The chemical that will be found in high levels in the blood of patients diagnosed with untreated diabetes mellitus would be glucose.
10. How does odor help in diagnosis of disease?
Odor of urine helps in diagnosing disease by merely alerting the patient that something is wrong. Because urine doesn’t have a very strong smell, if a whiff of something is particularly pungent when peeing, it may indicate that the patient could have an infection or urinary stones, which can create an ammonia-like odor. Diabetics might notice that their urine smells sweet because of excess sugar. Alkaline fermentation causes an ammoniacal smell, and patients with diabetic ketoacidosis produce a urine that may have a sweet or fruity odour. Other causes of abnormal odours are cystine decomposition (a sulphuric smell), gastrointestinal-bladder fistulae (a faecal smell), medications (eg, vitamin B6), and diet (eg, asparagus).
11. Define the following terms associated with urinalysis:
Glycosuria: Glucose normally is filtered by the glomerulus, but it is almost completely reabsorbed in the proximal tubule. Glycosuria occurs when the filtered load of glucose exceeds the ability of the tubule to reabsorb it (i.e., 180 to 200 mg per dL). Etiologies include diabetes mellitus, Cushing's syndrome, liver and pancreatic disease, and Fanconi's syndrome.
Ketonuria: Ketones, products of body fat metabolism, normally are not found in urine. Dipstick reagents detect acetic acid through a reaction with sodium nitroprusside or nitro-ferricyanide and glycine. Ketonuria most commonly is associated with uncontrolled diabetes, but it also can occur during pregnancy, carbohydrate-free diets, and starvation.
Hematuria: Hematuria can be glomerular, renal, urologic, and exercise-induced. Urologic causes of hematuria include tumors, calculi, and infections. Urologic hematuria is distinguished from other etiologies by the absence of proteinuria, dysmorphic RBCs, and erythrocyte casts.
Even significant hematuria will not elevate the protein concentration to the 2+ to 3+ range on the dipstick test. (23) Up to 20 percent of patients with gross hematuria have urinary tract malignancy; a full work-up with cystoscopy and upper-tract imaging is indicated in patients with this condition. (24) In patients with asymptomatic microscopic hematuria (without proteinuria or pyuria), 5 to 22 percent have serious urologic disease, and 0.5 to 5 percent have a genitourinary malignancy.
pH: Urinary pH can range from 4.5 to 8 but normally is slightly acidic (i.e., 5.5 to 6.5) because of metabolic activity. Ingestion of proteins and acidic fruits (e.g., cranberries) can cause acidic urine, and diets high in citrate can cause alkaline urine. (15-17) Urinary pH generally reflects the serum pH, except in patients with renal tubular acidosis (RTA). The inability to acidify urine to a pH of less than 5.5 despite an overnight fast and administration of an acid load is the hallmark of RTA. In type I (distal) RTA, the serum is acidic but the urine is alkaline, secondary to an inability to secrete protons into the urine.
Type II (proximal) RTA is characterized by an inability to reabsorb bicarbonate. This situation initially results in alkaline urine, but as the filtered load of bicarbonate decreases, the urine becomes more acidic. Determination of urinary pH is useful in the diagnosis and management of UTIs and calculi. Alkaline urine in a patient with a UTI suggests the presence of a urea-splitting organism, which may be associated with magnesium-ammonium phosphate crystals and can form staghorn calculi. Uric acid calculi are associated with acidic urine.
Hemoglobin: The presence of free hemoglobin in the urine, an abnormal finding, that may make the urine look dark. Hemoglobin in the urine is termed hemoglobinuria. Hemoglobin is the protein in the red blood cells which carries oxygen from the lungs to the tissues of the body and returns carbon dioxide from the tissues to the lungs.
The iron contained in hemoglobin gives red blood cells their characteristic color. Red blood cells are normally taken out of circulation after approximately 4 months; they are trapped and disassembled in the spleen, bone marrow, and liver. If, however, red cells hemolyze (break down) within the vascular system, the components are set free in the blood stream. Free hemoglobin is bound by haptoglobin (another protein) and reprocessed. But if the level of hemoglobin in the blood rises above the ability of haptoglobin to reclaim it, hemoglobin begins to appear in the urine -- there is hemoglobinuria. Hemoglobinuria is a sign of a number of conditions including: acute nephritis, burns, kidney cancer, malaria, sickle cell anemia, a transfusion reaction, tuberculosis of the urinary tract, and many other conditions.
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