Urinalysis and Laboratory Results

Medical Laboratory Testing Basic Principles

• 70% of medical decisions rely on lab test results.
• Future physicians need to understand lab test ordering for patient care and cost-effectiveness.
• Proper sample collection, handling, and transportation are crucial for accurate results.
• Communication with lab specialists is essential for better patient care.

Laboratory Testing Cycle (Laboratory Work Flow)

• The lab testing cycle comprises three phases: pre-analytical, analytical, and post-analytical.
• Pre-analytical phase errors are the most frequent cause of lab test errors (62-76%).
• Pre-examination phase includes test selection, sample collection, and transport.
• Examination phase involves laboratory analysis.
• Post-examination phase comprises report creation, transport, and result interpretation.

The Three Phases of Laboratory Testing

• Pre-analytical Phase: Test ordering, specimen collection, transport, and processing.
• Analytical Phase: Testing.
• Post-analytical Phase: Results transmission, interpretation, follow-up, and re-testing.

Most Inaccurate Results

• Most inaccurate results stem from errors in the pre-analytical phase.

Percentage of Laboratory Errors Reported in Each Phase of Laboratory Testing Cycle

• Pre-analytic: 62-76%
• Analytic: 6-15%
• Post-analytic: 18-30%

From the Patient to the Lab - Common Errors

• Incorrect test ordering.
• Request form errors.
• Incorrect patient identification.
• Incorrect patient preparation (fasting, diet).
• Inaccurate sample timing.
• Sample poorly/incorrectly taken.
• Wrong type of sample.
• Incorrect containers (under-filling/over-filling).
• No labeling/mislabeling of samples.
• Incorrect storage/transport (temperature/delay).
• Loss, breakage, and leakage.

Laboratory Tests Turnaround Time (TAT)

• TAT is a critical measure of lab performance.
• Different definitions of TAT exist among clinicians and lab personnel.
• Lab personnel define TAT as the time from sample receipt to report generation.
• Clinicians define TAT as the time from test requisition to receipt of the report.
• TAT should be clearly defined in each institution.

Laboratory Tests Turnaround Time (TAT) - Reasons for TAT Importance

• Supports patient-centered care.
• Important for accurately evaluating lab performance.
• Contributes to patient and physician satisfaction.
• Delays are a major source of complaints from lab users.
• TAT is a critical lab performance metric.

Laboratory Test Ordering

• Crucial for accurate patient care.
• Key considerations in test ordering include the rationale for testing, appropriate test selection, and accurate request form completion.

Indications for Ordering Laboratory Tests

• Confirming a diagnosis.
• Helping in differential diagnosis.
• Evaluating prognosis.
• Monitoring therapy.
• Screening for a disease.

Proper Completion of Laboratory Request Form

• Request forms must contain: patient's full name, date of birth, gender, medical record number, date of request, clinical diagnosis, ordered tests, and physician's signature.

Sample Collection

• Quality and safe patient care relies on proper patient identification.
• Correct timing and handling of samples are vital to accurate results.
• Proper procedures for sample collection are important.
• The use of various colored sample tubes corresponds to specific tests.
• Correct sample tubes are essential for the proper test.
• Proper labeling and pairing of samples with requisition forms is essential.

Proper Patient Identification

• Proper patient identification is crucial to international lab safety.
• Patient identifiers used include full name, date of birth (DOB), and medical record number.

Proper Sample Collection - General Considerations

• Follow patient instructions (fasting for certain tests).
• Use appropriate sampling times for specific tests (e.g., cortisol).
• Collect samples from suitable veins.
• Observe infection control procedures (short tourniquet time).
• Use the correct tube for the test.
• The tube must be labeled in front of the patient by the person who collected the sample.

Basic Phlebotomy Supplies

• Requisition
• Gloves
• Tourniquet
• Needle/Syringe
• Tubes
• Alcohol
• Cotton or Gauze
• Bandage or Tape
• Proper labeling

Proper Sample Collection - Practices to Follow

• Sample collection, collection and label samples for one patient at a time.
• Proper tubes correctly.
• Maintain proper sample mixing procedure (invert 5-8 times, do not shake.)

Proper Sample Labeling

• Sample tubes should be labeled immediately after collection with bar codes or manually using two patient identifiers.
• Identifiers include full name, date of birth, or medical record number.

Proper Sample Transportation

• Place samples in a biohazard transport box.
• Transport the sample immediately to the lab along with the request form.
• Do not carry samples by hand or in pockets.

Laboratory Sample Delivery

• The lab verifies that tubes are firmly covered, labels are complete and match requests, sample volume is appropriate, sample quality is suitable, and sample type is correct for requested tests.

Sample Rejection Criteria

• Unlabeled or incompletely labeled samples.
• Mismatched labeling and requisition.
• Insufficient sample volume.
• Unsuitable sample (hemolyzed specimen).
• Insufficient volume of preservative.
• Prolonged transport times.
• Improper collection techniques

Laboratory Test Results Interpretation

• Laboratory results must be interpreted within the context of a person's general health status as compared to reference values.
• Reference intervals may vary based on age, sex, race, pregnancy, or the test methodology used.
• Variability in test results is expected and should be considered by the clinician.
• Sources of variability include patient posture, diet, medications, and others.

Reference Values

• Reference intervals are used to distinguish between health and disease.
• Types of reference values include reference intervals (ranges), decision cut-offs (positive or negative), and therapeutic ranges.

Variability of Laboratory Test Results

• Different laboratories may generate different results due to the methods and techniques used.
• Biological, pre-analytical, analytical, and post-analytical factors can contribute to test result variability in repeated measurements within and between individuals

Variables Affecting Test Results

• Patient variables (diet, body mass, age, medications, gender, smoking, exercise, race, dehydration)
• Specimen collection variables (posture, diurnal variations, time of collection, fasting status, tourniquet, presence of IVs, capillary vs venous)
• Specimen handling variables (hemolysis, lipemia, centrifugation, processing time, temperature, sunlight, evaporation, aliquoting, labeling, transport conditions, order of draw)

How to Establish Diagnosis Based on Laboratory Test Results

• For some tests, the interpretation of lab results is straightforward (e.g., monitoring anticoagulant therapy).
• In other cases, a renal panel may be used for diagnosis, screening or monitoring.
• Panel test results can suggest a pattern of conditions.
• Hypothesis must be established by correlating the lab results with clinical evaluation.

Medical Algorithms

• Medical algorithms are helpful in the sequential process of testing needed to rule out various possible conditions.
• Example: an algorithm for anemia evaluation based on Hemoglobin concentration, PCV, RBCs, MCV, and others

Critical Results

• Critical values are test results that significantly deviate from the normal reference range and may pose a life-threatening risk.
• Health care providers must act immediately upon receiving critical values.
• Appropriate communication channels for critical values should be established.
• Example critical values include glucose, hemoglobin, platelets, and INR.

Complete Blood Count (CBC) Interpretation/Anemia

• CBC is a routine blood test to measure different components and to determine the possibility of anemia
• Various medical parameters of a CBC are used to determine anemia such as hemoglobin, haematocrit, RBCs count, RBC Indices, WBCs total count, WBCs different count, Platelet count

Blood Groups

• Blood types are categorized as A, B, AB and O based on the presence or absence of A and B antigens on red blood cells (RBCs).

Blood Group System and Compatibility

• Blood compatibility is crucial for safe blood transfusions.
• Blood type O is the universal donor (compatible with all types), and type AB is the universal recipient (accepts blood from all types).

Basic Blood Components Processing

• Whole blood is processed to separate components (packed RBCs, platelet rich plasma, fresh frozen plasma, cryoprecipitate, etc.).
• Soft and Heavy spins are used in the processing for various components

Rationale Use of Blood Components

• Different blood components have varying storage requirements and shelf lives. - Red cells and plasma have different storage times.

Blood Components Modifications

• Modifications like leucoreduction, washing, irradiation, and freezing are applied to improve blood safety and efficacy.

Blood Transfusion Reactions

• Adverse events or complications related to blood transfusions.
• Immunological reactions (both acute and delayed hemolytic reactions, febrile nonhemolytic reactions, allergic reactions, transfusion-related acute lung injury (TRALI), transfusion-associated graft-versus-host disease).
• Non-immunologic reactions (bacterial contamination, circulatory overload, physical/chemical hemolysis).

Transfusion Reactions Workup

• Steps to follow when a transfusion reaction is suspected.
• First, stop the transfusion and perform a clerical check.
• Draw a post-transfusion sample for tests (ABO/Rh testing, hemoglobinemia, others).
• Further testing (if necessary) include haptoglobin, LDH, bilirubin, and urine HGB for diagnosis

Urinalysis

• Urinalysis includes physical, chemical, and microscopic examinations to assess urine constituents.
• The technique requires proper sample handling to ensure accurate results.

Urinalysis - Physical Examination

• Volume (normal range: 800-2000 mL/day; abnormal values can indicate kidney disease).
• Odor (normal: urineferous; abnormal: fruity, ammonia).
• Color (normal: pale yellow; abnormal: colorless, orange, red, black).
• Aspect (normal: clear; abnormal: turbid).
• Specific gravity (normal range: 1015-1025): abnormal values can indicate kidney issues, dehydration, or other metabolic disorders)
• pH (normal range: 5-6.5): a change in pH may indicate an issue in the urinary tract

Urinalysis- Chemical Examination

• Chemical examination assesses urine using dipsticks with color-coded results
• Dipsticks indicate the presence of substances like glucose (diabetes mellitus), ketones (diabetes or starvation, bilirubin (liver disease), blood (urine infection, tumors, stones), protein (kidney disease), urobilinogen (liver issues), nitrite (urinary tract infection), and others

Urinalysis- Microscopic Examination

• Microscopic examination of urine sediment identifies cells (red blood cells (RBCs), white blood cells (WBCs), epithelial cells, casts), crystals (oxalates, urates, phosphates), and organisms.
• Example: microscopic hematuria (RBCs greater than 5 per high power field) could indicate glomerular damage, tumors, urinary tract stones or infection.

Point of Care Testing (POCT)

• POCT (point-of-care testing) is a testing method that can be done at or near the patient's bedside.
• POCT is generally performed outside of a central laboratory and includes tests like urine dipsticks, pregnancy tests, and glucose meters.
• Advantages include reduced turnaround times, minimized delays, and direct results that facilitate better patient care decisions.
• Some disadvantages include potential errors, required administrative efforts (training, certification of staff).

Laboratory Test Panels

• Test panels group related tests performed routinely to assess a person's overall health status.
• Examples of panels include Basic Metabolic Panel (BMP), Comprehensive Metabolic Panel (CMP), Electrolyte Panel, Lipid Panel, Hepatic Panel (liver function tests), Renal Panel (kidney function tests), and Thyroid Panel (thyroid function tests)

Infection Control

• Infection control refers to a variety of practices and procedures for reducing the risk of infection spreading, especially in healthcare facilities.
• A hospital acquired infection is an infection contracted in a healthcare setting that wasn't incubating when the patient was admitted

Chain of Infection

• The chain consists of an infectious agent (pathogen), reservoir (where the pathogen lives), portal of exit, mode of transmission, portal of entry, and susceptible host (person who gets infected)

Standard Precautions

• Standard Precautions are a set of infection control practices in healthcare settings to prevent the spread of infectious diseases, especially through direct contact (e.g. via hands of healthcare workers).
  • Includes hand hygiene, safe injection practices, appropriate use of personal protective equipment and appropriate waste disposal.

Personal Protective Equipment (PPE)

• PPE (Personal Protective Equipment) is specialized clothing or equipment specifically to protect individuals against infectious microorganisms.

Antibiotic Stewardship

• Antibiotic stewardship is a systematic approach to wisely using antimicrobial agents so better treatment outcomes for patients, and reducing the development of antibiotic resistance.
• Physicians must obtain appropriate cultures in suspected infections and promptly use antibiotic therapy
• Overuse of antibiotics results in adverse effects & increased likelihood of multidrug resistant bacteria (e.g. super infections with Clostridium difficile).
• Aims to prevent antibiotic resistant bacteria.