AUBF-lec W2 Intro to Urine

Urine

A fluid biopsy that provides information about metabolic processes in the kidney and other organs. It is easy to collect, analyze, and interpret, and is an ultrafiltrate of plasma.

Kidney

The only organ that can be evaluated non-invasively through urine examination.

Urinalysis

The testing of urine using procedures that are expeditious, reliable, accurate, safe, and cost-effective. It includes physical observation, reagent strip analysis, and microscopic examination.

History of Urinalysis

The analysis of urine has been practiced since ancient times, with references found in cavemen drawings and Egyptian hieroglyphics. Early physicians used urine examination to diagnose diseases.

Albuminuria

The presence of protein or albumin in urine. Discovered by Frederik Dekker in 1694, it is an important component of urine biochemical examination.

Urine Formation

The kidney filters approximately 170,000 mL of plasma to produce an average of 1,200 mL to 1,500 mL of urine per day. It is formed as an ultrafiltrate of plasma by the glomerulus.

Urine Composition

The composition of urine depends on factors such as diet, hydration, physical activity, endocrine functions, and body position. It contains 95% water and 5% solutes, including organic and inorganic substances.

Urea

The major metabolic waste product of protein and amino acids. It accounts for nearly half of the total dissolved solids or solutes found in urine.

Creatinine

A product of muscular metabolism. Its level in urine is monitored to assess kidney function.

Sediment Examination

The microscopic examination of urine sediment, which includes formed elements such as cells, casts, crystals, mucus, and bacteria. It serves as the gold standard to confirm the results of physical and chemical examinations.

Importance of Urinalysis

Urinalysis is important because urine is readily available and easily collected. It provides information about the body's major metabolic functions and can aid in the diagnosis, screening, and monitoring of diseases.

Reasons for Performing Urinalysis

Urinalysis is performed to aid in the diagnosis of diseases, correlate different test results, screen asymptomatic populations for undetected disorders, and monitor the progress of disease and effectiveness of therapy.

4 Parts of Routine Urinalysis

Specimen evaluation, physical examination, chemical examination, and sediment examination. These steps help assess the integrity and composition of urine.

Oliguria

A decrease in urine output, which may indicate kidney dysfunction or decreased blood flow to the kidneys.

Anuria

Cessation of urine flow, which can result from serious kidney damage or decreased blood flow to the kidneys.

Nocturia

An increase in the nocturnal excretion of urine.

Polyuria

An increase in daily urine volume, which may indicate certain conditions or excessive fluid intake.

Specimen Handling

Proper handling of urine specimens is important to maintain their integrity and prevent changes in composition. Correct handling procedures should be followed to ensure accurate test results.

Specimen Integrity

Maintaining the integrity of urine specimens through proper handling and preservation is crucial for accurate test results.

Specimen Testing Time

Urine specimens should be tested within 2 hours of collection to ensure accurate results.

Refrigeration

Specimen that cannot be delivered and tested within 2 hours should be refrigerated to preserve its integrity.

Chemical preservative

An appropriate chemical preservative can be added to a specimen that cannot be delivered and tested within 2 hours to maintain its stability.

Bacteria

Most of the biochemical changes in a specimen are related to the presence and growth of bacteria.

Sterile urine

Urine that passes through the urethra is no longer sterile due to normal flora.

Glucose utilization

Some bacteria utilize glucose present in urine, causing a decrease in its concentration.

Unpreserved urine changes

Unpreserved urine undergoes changes in color, clarity, odor, pH, and the concentration of various analytes due to bacterial growth and metabolic processes.

Specimen preservation

Refrigeration is the most commonly used method of preserving urine specimens, but chemical preservatives can also be used to decrease bacterial growth and metabolism.

Urine preservatives

Different preservatives have advantages and disadvantages in preserving specific components of urine, and the choice of preservative depends on the desired tests and components to be preserved.

Specimen collection

Urine should be collected in clean, dry, leak-proof, and disposable containers. Sterile containers should be used for culture and sensitivity testing. The container should be properly labeled with patient information and collected in sufficient quantity for testing.

Specimen confirmation

Specific gravity, pH, temperature, and creatinine levels can be used to confirm the authenticity of a urine specimen.

Types of urine specimen collection

The three basic types of urine specimens are first morning urine, random urine, and timed urine, each with its own purpose and indications.

First morning urine

First morning urine is the ideal screening specimen, collected immediately upon arising and reflecting the metabolism of the previous day. It is useful for detecting abnormalities and ensuring accurate pregnancy test results.

Orthostatic proteinuria

A type of proteinuria that occurs when standing for a prolonged period of time.

True proteinuria

A clinically significant type of proteinuria.

Fasting specimen

A urine specimen collected after a period of fasting, typically the second morning voided specimen.

2-hour postprandial specimen

A urine specimen collected 2 hours after eating, primarily used to monitor insulin therapy in diabetes mellitus patients.

Glucose tolerance specimen

A urine specimen tested for glucose and ketones, used to interpret the patient's ability to metabolize glucose.

Timed specimen

A urine specimen collected over a specific period of time to obtain accurate quantitative results.

24-hour urine specimen

A timed urine specimen collected over a 24-hour period to identify solutes present.

Catheterized specimen

A urine specimen collected via a catheter, commonly used for bacterial culture.

Midstream clean-catch specimen

A less invasive method of collecting urine for culture and sensitivity, obtained by catching the mid-portion of urine after appropriate cleansing.

Suprapubic aspiration

The most invasive method of collecting sterile urine, obtained by puncturing the urinary bladder under ultrasound guidance.

Prostatitis specimen

A urine specimen used to evaluate infection in the prostate gland.

Three-glass collection

A method of collecting three urine samples (glass 1, glass 2, and glass 3) to diagnose prostatic infection.

Stamey-Mears four-glass localization method

A method of collecting four urine samples (VB1, VB2, EPS, VB3) to differentiate between urinary tract infection and prostatic infection.

Pre- and post-massage test (PPMT)

A test that compares the bacterial count in the pre-massage and post-massage urine specimens to diagnose prostatitis.

PPMT

Process where the bacteria and WBC of pre-massage and post-massage are checked.

Prostatitis

Condition where WBC and bacteria increase 10x higher after massage.

Chain of Custody (COC)

Process that provides documentation of proper sample identification from collection to receipt of laboratory results.

Drug Specimen Collection

Most vulnerable part of a drug-testing program.

Tampering

Any alteration of the specimen, such as substitution, adulteration, or dilution.

False-Negative Result

Result indicating the absence of drugs when they are actually present, even with a small amount of water contamination.

Witnessed Collection

Drug testing conducted in the presence of a witness, typically for drug suspects.

Volume

The recommended amount of urine to collect for drug testing, typically 30-45 mL.

Temperature

The acceptable range for urine temperature during collection, between 32.5°C to 37.5°C.

Fresh Urine

Preferred over aged urine for drug testing.

Urine Drug Specimen Collection Procedure

Step-by-step process followed during urine collection for drug testing.

Bluing Agent

Dye added to toilet water reservoir to prevent adulterated specimens.

Photo Identification

Document provided by the donor for identification purposes during drug testing.

Abnormal Color

Unusual appearance of urine that may indicate adulteration or dilution.

Specimen Identification Strips

Strips from the Chain of Custody form used to label the specimen bottle.

Specimen Bottle Seals

Seals on the specimen bottle that are initialed by the donor.

Laboratory-Specific Instructions

Instructions provided by the laboratory for packaging and handling the specimen bottles.

COC Copies

Copies of the Chain of Custody form distributed to appropriate personnel.