Urine Specific Gravity and Analysis

Composition of Urine

• Urine is an ultrafiltrate of plasma that does not reflect its composition due to resorptive and secretive processes, it is 95% water and 5% solutes.
• Organic components of urine include urea (most abundant), creatinine, uric acid, ammonia, and undetermined nitrogen.
• Inorganic urine components are chloride (most abundant), Na+, K+, Ca2+, phosphates, and sulfates.

Urine Volume

• Daily urine output varies randomly (600-2,000mL/day) depending on hydration status.
• Average daily output is between 1,200-1,500mL/day, with a day/night ratio of 2-3:1.
• Polyuria involves abnormally increased urine output (>2.5L/day), seen in cases of diabetes mellitus (with high specific gravity due to osmotic diuresis) and diabetes insipidus (with low specific gravity).
• Oliguria constitutes decreased urine output (<400mL/day), associated with dehydration, renal insufficiency, heart disease, calculi, and kidney tumors, and may result from decreased renal blood flow or obstruction.
• Anuria refers to the complete cessation of urine production, linked to severe acute nephritis, mercury poisoning, obstructive uropathy, and kidney failure.
• Nocturia is >500mL of urine excretion during the night with a specific gravity of <1.018, may be pathologic or physiologic (pregnancy, prostatic hyperplasia).
• Diuresis involves transient/temporary polyuria from substances with a diuretic effect (drugs, alcohol, caffeine), leading to increased water excretion.

Types of Urine Specimen

• First morning specimen is best for routine urinalysis due to its concentration, reducing chances of false negatives, also used for pregnancy tests and orthostatic proteinuria. Orthostatic proteinuria (aka Postural proteinuria)
• A benign proteinura common in young adults after periods standing
• Disappears in horizontal positions due to increased pressure on the renal vein while in the vertical position
• A randome urine sample is taken at the end of hours of standing then a first morning after horizontal position is taken which should yield not postive results depending on sample

Random Specimen

• Used for routine urinalysis, acceptability check, low specific gravity leads to its rejection to avoid false negatives.

Timed Specimen

• Is important that collection starts and ends with an empty bladder, used for quantitative techniques (hormone studies, creatinine clearance test).
• There is 5 hour urine specimen used to distinguish maldigestion and malabsorption in D-xylose test
• There is the 2h specimen for the afternoon (2-4PM) and used for urobilinogen determination because the peak of urobilinogen is in the afternoon.
• Amber bottle is used urobilinogen due to the photosensitivity of urobilinogen. 12h specimen is for Addis' count and this technique used to employ hemocytometry to count formed elements in urine, formalin is used to preserve

Specimens for DM Screening/Monitoring

• Second morning specimen after fasting is used, discarding the first voiding to eliminate metabolites, +/- ketones are important parameter.

2-h Post-prandial Specimen

• Useful for detecting glycosuria/glucosuria.

GTT Urine

• Previously used along with blood in routine OGTT, not used now.

Drug Testing Specimen

• COC is used with standardized form, follow chain of custody which requires traceability and accountability.
• Collected volume must be 30-45 mL within 4 minutes, temperature should be 32.5-37.7 C
• If out of range, recollect and notify the supervisor because it could be indicative of specimen adulteration.
• Ensure specimen integrity with bluing agent in unwitnessed collection; ASC authorization removes the need for it.

Collection Techniques

• Midstream Clean-Catch: yields sterile specimen for bacterial culture, utilizing cleansing and discarding first fraction (external genital).
• Catheterization: yields sterile specimen
• Urethral Catheterization: enables kidney evaluations using catheter position.
• Suprapubic Aspiration: yields sterile specimen for bacterial culture and use for cytology studies.

Prostatitis Specimen Collection

• Three-Glass Collection: tubes one and two capture kidney and bladder elements, tube three contains prostatic elements, tube to yields a diagnosis if containing a significant number of WBC and bacteria as opposed to tube
• Four-Glass Collection/Stamey-Mears Technique: contains EPS (Express Prostatic Secretion)

Specimen Collection and Handling

• First morning midstream clean-catch is preferred;
• Capacity of container should be 50 ml
• Container should be clean, sterile, leak proof, dry, transparent, and need 10-15 ml volume.
• Label container body with: patient full name and date/time of collection,
• Analysis should be done less than 2 hours because urine older than this is not acceptable

Preservation Techniques

• Used for delays, most common is Refrigeration which maintains acid pH and bacteriostatic until 24 hours;
• Disadvantage is: amorphous material (urates in acidic, phosphates in alkaline).
• If there's a delay in analysis use refrigeration in a 24hrs, if exceeded use chemical substances like formalin, thymol, etc.
• Other methods: Formalin, Sodium Fluoride, Boric Acid and Saccomanno fixative
• In acceptability criteria, a urine must be transported, process or analyzed within 2 hours of collection, improper is if more than 2 hours

Collection Kits

• Collection kits: comes with collection container and its designated vacutainer tube.
• Yellow top tube/ Plain tube - does not contain any additive which means that the specimen in this tube should be refrigerated within 2 hours prior to collection if analysis will be delayed
• Gray top tube - used for culture and sensitivity.
• Cherry red/ yellow top (speckled) contains sodium propionate, ethyl paraben, and chlorhexidine. that last 72hours for keeping time
• These tubes are compatible with urinalysis workstations which are automated machines

Changes in Unpreserved Urine

• In unpreserved urine, if analysis is delayed, the same samples is unsuitable and older than 2 hours for analysis
• In stored urine, oxidation and changes can occur and lead to certain inaccuracies

Physical Examination of Urine

Color:

• Primary cause of color change in urine is oxidation., can change color like blue or brown depends on sunstance, Odor:
• Becomes ammoniacal and odor intensify. pH:
• Becomes more alkaline. Nitrite
• Indicates bacterias that contains the reduce in nitrate. Bacterias
• Most of the changes in unpreserved urine are related to bacteria. Clarity Decreases of test that is result with more turbid. Glucose Decreases due to glycolysis cause bacteria Ketone Decreases to volatilization of acetone. Bilirubin Photosensitivie oxidixez to biliverdin Urobilinogens Oxidized to biliverdin from photons RBC and WBC Trichomonas
• Disintegrates as become alkaline stands
• Trophozoites such as Trichomonas vaginalis loss it motility
• Freshners of specimens

Normal and Variations in Urine Color

• Color varies depending on pigment, colorless, or medicine color: Collorless- recent food consumption of fluids Pale yellow- recent fluids and diuretics Bilirubinura- yellow foam Bluegreen- Amitriptyline, methocarbamol, clorects,phenol Brown - Phenol derivative to posoning Pinkred or redbrown - Beets, menstrual contamination, rifampin
• Causes: fluid intake, bilirubin, and other pigmentation.
• Transparency is clear: no visible particulates or transparent

Causes of variations in transparency

• causes from epthileal cells squamous, mucus and vasinal
• caused by RBC ,WBC adn RTE cells (non squamous cells)

Abnormal crystals

• urates = brick dust;
• Lymph fluid- chyluria that by thoraic or cancer

Methods to Measure Specific Gravity

• Methods of density that measure in blood are Urinometry, Refractormetry and harmonic oscillation density Specific gravity is determined by what the concentration of amount of water within renal fluid. Normal values varies from 1.0003, 1.035 and 1.050 and 1.025 Calibrating water or urinanater is by temperature and specific gravity through calculations

Odor

• The aroma is normally found in urine thats a newly tested test called aromatic which is tested Volatile acids used in specimen. variations in urine used volatile specimen.

Chemical Examination

• chemical examination of the urine in specific volume of collected specimen is to test to certain points, Hypersthenuria which > 1.010 to 1.035

B.PH

• PH is determined by to chemical testing, Double indicator reaction uses methyl red with M and chemstips, normality of the PH is from a range of 4.5-8.0

Indications of chemicals in urine

Acids- Hypoventilation,Dka,Diherra/Dehydration Alkaline- Transitent Alkalemia, Vegeterian and bacterial

Protein

• the glomerules fildration barrier to impermeable the protein values, only under 30 is considered. Protein urea is Low molecular Inter vessels homolisis Muscle and Tissue Infection

DCLUCOSE

normal level is less than 15mg, Reagent strips is normal to test Double Sequential Glycose is glucomic

Test the Microabluminuria. Michael test is inumunoassay Inomnuodi is inmunochoataic

Ketones

• Acetest test that is used glucose or glucose
• Ketone the to that acestoic,

BLood test

• Bllod test os hemariuar and reagent strips
• Meylbiums do not test pasima and normaly that are excretred are the easy

Testfor bilirubin

Icotest, which has tablet and are senstivie Hemeoic duanive do test biliibrun Bilirubin is compemnt of B1,

Urino billingen and ubg , is 1:0 Urobligen is nirmally t Unog is normally found in urine because UBG to that

NITRITE

• Used to test reagent strips, that comes that gram negative

Sensitivities to determine high numbers by chemical

Care Of a regent stripes

_ Must be secured at a room temperature less than 30

• must opaque that contain descents Techniques let the regrifrigeter of a well specemn Avoid remover

Specidic gravuity or urine

It's principle of poltelectlytes Urine or chemical with the range of M and C.

Questions about urine specific gravity, its measurement, and conditions affecting urine volume and concentration. Includes diabetes insipidus, polyuria, and proper urine collection methods. Covers expected urine volume ranges and the impact of standing samples.