Urinalysis and BSL Monitoring

Urinalysis and BSL Monitoring Urinalysis • Leukocytes are more specific to nitrates for presence of infections. Urine Dipstick Gross urine assessment • Urine colour - • Normal: pale to dark yellow -> depends on hydration status Red urine: haematuria Black urine: alkaptonuria Turbidity (cloudiness of urine) - Cloudy? Suggests infection or chyluria. - The presence of chyle in the urine, which results in a cloudy appearance. Most associated with lymphatic filariasis due to the development of a communication between the lymphatic system and the urinary tract. Another rare cause is partial nephrectomy. Urine dipstick • • • • • pH: 4.5 – 8 urine specific gravity - measures the ratio of urine density over pure water density (normal range 1.005 – 1.030) - high urine gravity: volume loss, heart failure, presence of large molecules (e.g., glucose) - low urine gravity: renal failure, diabetes insipidus - Specific gravity is different from urine osmolality in that it is determined by both the number and the size of the particles in the urine. In contrast, the size of particles does not influence the osmolality. heme: more than 90% for haematuria - low specificity: False positive tests for haematuria on dipstick are caused by hemoglobinuria or myoglobinuria. Leukocyte esterase (Enzyme made by white blood cells): enzyme produced by white blood cells that indicates UTI. Protein: proteinuria • • • • - False negative tests of proteinuria on dipstick occur in the case of multiple myeloma, hemoglobinuria, and myoglobinuria because low-molecular-weight proteins (i.e., light chains and small proteins) are not detected by the dipstick. - Glucosuria is a key defining in diabetes mellitus. Glucose Ketones Urobilinogen Nitrate - Diabetic ketoacidosis (complications od T1DM) Prehepatic jaundice and intrahepatic jaundice indicative of UTI caused by negative gram bacteria. Urine Microscopy • should always be examined with either a fresh one (1 hour within collection) or after preservation with boric acid in order to prevent bacterial overgrowth. • The sample should be collected as a “mid-stream” sample, this is particularly important in omen to avoid vaginal epithelial concentration. • Use phasic contrast to allow the morphology of cellular and crystalline components of the urine to be seen in greater detail. - If phasic contrast is not available -> results can be obtained by almost completely closing the diaphragm of the microscope or use a histological stain such as alcian blue to identify nucleated cells. Types of urine microscopy. 1. An un-centrifuged urine sample is examined within a counting slide to measure the number of cells within the urine sample. This is usually done using a special counting slide that contains a counting chamber of exact known volume. Counting the no of randomly distributed cells within this volume can be used to estimate the no of cells. For example, the no of leucocytes reported may be given as 10-100X106 / litre, meaning there are between 10-100 cells in a microlitre of urine (a microlitre is 10-6 L). 2. In specific cases, a ‘spun’ (centrifuged) urine sample is examined for the presence of abnormal crystals and casts. The urine sample is typically centrifuged at 3000 to 5000rpm for 3-5 minutes in a desktop centrifuge that concentrates the cells in a pellet at the bottom of the tube. Most of the ‘supernatant’ is then removed and the cells are mixed in a smaller volume, thus concentrating the sample, and making abnormal crystals and casts easier to see. Components of a phase contrast urine microscopy 1.Cellular components: • Urinary erythrocytes: - Normal urine typically contains small numbers of erythrocytes (<10x106/L) – these are typically dysmorphic (see below) and are presumably a product of normal glomerular filtration. - When the count is greater than 10x106 /L, particular attention should be paid to erythrocyte morphology - this is an important guide to their origin. - ‘Isomorphic’ erythrocytes show the normal biconcave disc morphology and can originate from any of the mucosal surfaces of the urinary tract (or be a contaminant such as in a menstruating female). - ‘Dysmorphic’ erythrocytes are formed by passage through the renal tubules of erythrocytes originating in the glomerulus. These erythrocytes show considerable distortion in their size, shape, and haemoglobin content. - An increased absolute number of dysmorphic erythrocytes is a sensitive marker of glomerular haematuria, although severe glomerular injury may also be associated with an increased number of isomorphic erythrocytes. • Urinary leukocytes: - Urinary leucocytes are typically larger than erythrocytes and have a granular cytoplasm, the ‘normal’ number of leucocytes in urine is <10x106/L. - Increased numbers of leucocytes can appear with infections of the urinary tract as well as urinary tract malignancy or stones. - In women, urinary samples may be contaminated by leucocytes from the vagina; an increase in the number of epithelial cells is usually indicative of vaginal contamination in these cases. • Urinary epithelial cells: - These cells may represent either tubular epithelial cells, transitional epithelial cells or squamous epithelial cells depending on their site of origin. - Lipid filled tubular epithelial cells ‘oval fat bodies’ may be seen in the urine of patients with significant proteinuria (usually in the nephrotic range). - An increased number (>10x106 /L) of squamous epithelial cells in a female patient is indicative of contamination of a midstream sample with vaginal epithelial cells and increases the chance of a false positive urine culture. 2.Urinary casts. • Best seen in centrifuged urine sample. ✓ Hyaline casts ➢ Tamm-Horsfall mucoproteins, things made by the kidney to prevent UTIs. ➢ Homogeneous, transparent, and eosinophilic ➢ Non specific finding and also found in healthy and dehydrated individuals ✓ Granular casts ➢ Caused by degeneration of cellular casts. ➢ Composed of a hyaline matric with cellular debris ➢ Larger than hyaline casts and have refractive droplets. ➢ Seen in acute tubular necrosis, glomerulonephritis, pyelonephritis and malignant nephrosclerosis. ✓ Muddy brown casts ➢ Made from similar things as granular casts. ➢ Appear with dark pigmentation. ➢ Specific for acute tubular necrosis ✓ Haemoglobin casts ➢ Result from degermation of red blood cells ➢ On pathology can see evidence of Hb pigment giving orange-yellow or redbrown colour ➢ Indicate intravascular haemolysis. ✓ White blood cell casts ➢ Strong indication of pyelonephritis ➢ Also seen in tubulointerstitial nephritis or glo merulonephritis or transplant rejection ✓ Fatty casts ➢ Indicate nephrotic syndrome. ✓ Red blood cells casts ➢ Cluster of RBCs ➢ glomerulonephritis and can also be seen in hypertensive emergency. - Crystals -> renal calculi Bacteria Yeasts 3.Urinary casts • Best seen in centrifuged urinary samples. • Urate crystals -> needle or diamond shaped. • Oxalate -> envelope or dumbbell shaped > helpful in suspected ethylene ingestion. However, may be present in the normal urine. • Phosphate -> coffin shaped -> may also be present in the normal urine. • Cystine -> rare and have hexagonal appearance and occur rarely -> typically occur in a patient with inherited disease cystinosis. BSL Estimation • hyperglycaemia: - if in DKA -> increased respiratory rate. - Increased urinary output. - Nausea. - Polydipsia. - Increased heart rate. - Rotten sweet fruity breath. Procedure 1. Ensure the patient’s finger is cleaned prior to measuring capillary blood glucose: It’s important that the skin over the site being tested has been cleaned, as substances on the skin can affect the accuracy of capillary blood glucose results (e.g., substances containing sugar). 2. Ask the patient to wash their own hands or alternatively you can clean the site with an alcohol swab (70% isopropyl). 3. Make sure the skin over the testing site has dried completely before performing capillary blood glucose measurement. 4. Turn on the capillary blood glucose monitor and ensure it is calibrated. 5. Load a test strip into the glucose monitor. 6. Don a pair of non-sterile gloves. 7. Pick up the lancet and carefully remove the protective cap. 8. Prick the side of the patient’s finger with the lancet and gently squeeze the finger from proximal to distal to produce a droplet of blood. Some guides advise cleaning away the first drop of blood, however, there is no evidence that this significantly impacts the reliability of blood glucose results. 9. Gently touch the tip of the test strip against the droplet of blood to allow it to be absorbed into the strip. 10. Apply gauze or cotton wool to the puncture site to stop the bleeding and ask the patient to maintain pressure over the site. 11. Safely dispose of the lancet into a sharps bin. 12. Dispose of the test strip and the cotton wool/gauze into a clinical waste bin. If the patient’s finger is still bleeding, keep the cotton wool or gauze in place and secure with some tape.