YEAR 1 - Clinical Chem Overview

Questions and Answers

What is the preferred method for urine specimen collection for chemical analysis?

Any random urine sample

A sample that is at room temperature for 4 hours

A well-mixed first morning specimen tested within 2 hours of collection (correct)

A sample collected after physical activity

What temperature condition should urine samples be kept at to prevent bacterial growth?

Refrigerated (correct)

At room temperature for 2 hours

Sub-zero temperatures

At normal body temperature

What is the minimum sufficient volume for urine samples intended for both macroscopic and microscopic analysis?

20 mL

5 mL

10 mL

12 mL (correct)

What factors can cause changes in urine composition if samples are left standing at room temperature?

Deterioration of formed elements and chemical composition changes Signup and view all the answers

What should be avoided to ensure urine samples remain uncontaminated?

Contamination from personal hygiene products Signup and view all the answers

What is the main reason for specimen preservation?

To avoid changes due to decomposition Signup and view all the answers

What effect does maintaining urine at low pH and high specific gravity (SG) have?

It slows down the deterioration of the sample Signup and view all the answers

How quickly do specimens start to decompose after collection?

Within 20-30 minutes Signup and view all the answers

Which preservative is most commonly used for urine specimen preservation?

Boric acid Signup and view all the answers

What is the primary role of boric acid in specimen preservation?

To detain the proliferation of harmful organisms Signup and view all the answers

What should be done with refrigerated specimens without preservatives after 48 hours?

They should be disposed of Signup and view all the answers

Which of the following does not serve as a preservative for urine specimens?

Sodium chloride Signup and view all the answers

What should be maintained to ensure quality urinalysis results?

Quality of specimens through refrigeration and transport Signup and view all the answers

What is the primary purpose of urinalysis testing?

To aid in the diagnosis of disease Signup and view all the answers

Which type of specimen is considered the best for urinalysis due to its concentration?

First morning specimen Signup and view all the answers

What precaution should be taken when collecting urinalysis specimens?

Secure the lid of the specimen container to prevent leakage Signup and view all the answers

What is a characteristic of random specimens in urinalysis?

The time of voiding must be recorded Signup and view all the answers

How does diurnal variation affect urinalysis results?

Results may differ due to variations in urine composition at different times Signup and view all the answers

What is included in the urinalysis testing procedures?

Macroscopic evaluation and chemical testing Signup and view all the answers

What most commonly characterizes the first morning specimen?

It is collected immediately after waking and reflects concentrated urine Signup and view all the answers

Which of the following is NOT a reason for conducting a urinalysis?

To monitor the severity of a head injury Signup and view all the answers

What type of specimen collection is used for specific timing of analysis?

Timed specimen Signup and view all the answers

What is the main focus of chemical reagent testing in urinalysis?

To identify the presence of specific substances in urine Signup and view all the answers

What does a 6 Sigma performance indicate regarding errors in tests?

3 errors in every million tests Signup and view all the answers

Which statement best reflects the relationship between Sigma, precision, and accuracy?

Higher Sigma values indicate fewer errors and better precision. Signup and view all the answers

What is the impact of achieving excellent precision and accuracy in testing?

It decreases the likelihood of errors occurring. Signup and view all the answers

What are common consequences if a method fails to meet precision and accuracy standards?

Replacement of methods or analyzers may be required. Signup and view all the answers

What does the formula for Sigma account for?

Total allowable error, bias, and coefficient of variation. Signup and view all the answers

If a test is built to be precise and accurate, what can be expected regarding QC rules?

Fewer QC rules would be needed. Signup and view all the answers

Which of the following is a crucial criterion for the evaluation of lab methods and equipment?

Linearity of the test method. Signup and view all the answers

What is typically true about most lab methods today?

They are commercially developed. Signup and view all the answers

What indicates an increased risk of renal disease in a patient?

Increased levels of mucoproteins in urine Signup and view all the answers

What condition could cause a spike in protein levels in urine aside from kidney disease?

Engaging in physical exercise Signup and view all the answers

Which protein is most reliably detected by urine dipstick strips?

Albumin Signup and view all the answers

What could cause a false positive result in protein testing?

Alkaline urine pH Signup and view all the answers

Which of the following circumstances could lead to a false negative protein test?

Dilute urine samples Signup and view all the answers

Which of the following statements about glycosuria is correct?

It occurs when blood glucose levels exceed 9 mmol/L. Signup and view all the answers

What factors influence the presence of glucose in urine?

Blood glucose level and tubular reabsorption Signup and view all the answers

What is a characteristic feature of albuminuria?

It signifies potential kidney damage. Signup and view all the answers

Study Notes

Urinalysis Overview

Urinalysis involves testing urine through macroscopic evaluation, physical measurements, chemical reagent testing, and microscopic examination.
Aids in diagnosing diseases, screening for conditions, monitoring disease progression, and evaluating therapy effectiveness.
All specimens treated as infectious; Standard Precautions must be followed.

Specimen Collection

Emphasis on hand washing and proper cleanliness is essential.
Specimens must have secure lids to prevent leakage.

Types of Specimens

Random Specimens: Collected anytime; time of voiding is recorded to account for diurnal variation.
First Morning Specimen: Collected first thing in the morning; most concentrated and reliable for chemical analysis.
Timed Specimen: Collected at specific times; important for stringent transport conditions.

Specimen Preservation

Preservation prevents decomposition; low pH and high specific gravity can slow deterioration.
Urine can decompose within 20-30 minutes due to bacteria producing ammonia.
Refrigerated specimens without preservatives should not be analyzed after 48 hours.
Boric Acid: Common preservative that reduces false positives by deterring bacterial growth.
Other preservatives include HCL, Chlorohexidine, and Formalin for various needs.

Specimen Requirements/Acceptability

High-quality specimens essential for accurate results; preferred first morning specimens should be tested within 2 hours of collection.
Urine should be shielded from light to prevent degradation of sensitive constituents.
Minimum volume for analysis is usually 12mL, preferably 50mL, with sterile, leak-proof containers required.

Protein Testing in Urine

Increased protein levels may indicate renal disease; affected by physical exercise or fever.
Urinalysis test strips are sensitive primarily to albumin; correlation with specific gravity is crucial.
False Positives: Can occur due to alkaline pH, prolonged dipstick exposure, cleaning agents, blood, or high bilirubin levels.
False Negatives: May result from diluted urine or the presence of proteins other than albumin.

Glucose and Reducing Substances

Glycosuria/Glucosuria: Indicates significant glucose presence; depends on blood glucose levels and filtration/reabsorption issues.
Glomerular permeability changes can lead to abnormal substance loss.

Sigma Quality Control (QC)

Six Sigma level indicates high precision, equating to 3 errors per million tests.
Three Sigma suggests lower precision with more errors (26,674 per million).
QC rules minimize errors; fewer rules required when assay accuracy is high.
Sigma calculation involves total allowable error, bias, and coefficient of variation.

Method Evaluation

Lab methods and equipment must meet specific criteria before patient testing.
Evaluation is necessary for outdated methods or analyzers.
Most laboratory methods today are commercially developed, emphasizing the need for linearity in testing.

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Description

This quiz explores the essentials of urinalysis, including specimen collection techniques and preservation methods. Participants will learn about different types of urine specimens and the importance of maintaining cleanliness during collection. Mastering these concepts is crucial for effective disease diagnosis and monitoring.