What are the common laboratory tests utilized in urgent care settings?

Common Laboratory Tests in Urgent Care Settings

Urgent care facilities routinely utilize a core set of laboratory tests including complete blood count (CBC), comprehensive metabolic panel (CMP), urinalysis, blood glucose, and coagulation studies, with additional testing guided by specific clinical presentations rather than routine protocols. 1

Core First-Line Laboratory Tests

Hematologic Testing

• Complete Blood Count (CBC) with differential is the most frequently ordered test in urgent care settings, providing essential information about infection, anemia, and hematologic abnormalities 1, 2
• Platelet count is routinely included to assess hemostatic function and bleeding risk 1
• CBC components evaluate white blood cell count, hemoglobin, hematocrit, and red blood cell indices (MCV, RDW) 3, 4

Metabolic and Chemistry Panels

• Comprehensive metabolic panel (CMP) assesses fluid and electrolyte status, renal function (BUN, creatinine), and liver function 1
• Blood glucose measurement is essential for evaluating altered mental status, diabetic emergencies, and strokelike symptoms 1
• Serum electrolytes (sodium, potassium, chloride, bicarbonate) identify imbalances that can produce various acute symptoms 1

Urinalysis and Urine Studies

• Urinalysis with microscopy evaluates for urinary tract infection, renal dysfunction, and hematuria 1
• Leukocyte esterase and nitrite testing by dipstick provides rapid screening for UTI 1, 5
• Urine cultures should be reserved for symptomatic patients rather than ordered routinely 1, 5

Coagulation Studies

• Prothrombin time (PT)/INR and activated partial thromboplastin time (aPTT) assess bleeding risk and anticoagulation status 1
• These tests are particularly important before procedures or when bleeding disorders are suspected 1

Condition-Specific Testing

Cardiac Evaluation

• Cardiac biomarkers (troponin, CK-MB) for suspected acute coronary syndrome 1
• Electrocardiogram (ECG) is standard for chest pain, palpitations, or suspected cardiac events 1

Infection Workup

• C-reactive protein (CRP) or procalcitonin (PCT) may be used when bacterial infection probability is low-to-intermediate to guide antibiotic decisions 1
• However, these inflammatory markers should not be used to rule out infection when clinical suspicion is high 1
• Blood cultures (minimum two sets from different sites) when bacteremia is suspected 1

Toxicology and Substance Screening

• Urine drug screens should be obtained based on clinical indication rather than routinely 1
• Studies show routine toxicology screening in psychiatric patients has minimal utility, with only 5% positive results and no management changes 1
• Blood alcohol level when intoxication is suspected 1

Additional Selected Tests

• Pregnancy test for women of childbearing age with abdominal pain or before certain procedures 1
• Thyroid function tests (TSH) for suspected thyroid disorders presenting with various symptoms 1
• Liver function tests when hepatobiliary disease is suspected 1
• Lipase/amylase for suspected pancreatitis 1

Critical Pitfalls to Avoid

Over-Testing Without Clinical Indication

• Do not order diagnostic tests at regular intervals (such as daily) but rather in response to specific clinical questions 1
• Routine laboratory testing without clinical indication increases costs, causes iatrogenic anemia from phlebotomy, and leads to unnecessary transfusions 1
• The CBC and basic metabolic panel should be ordered based on clinical need, not as routine screening 6

Inappropriate Use of Screening Tests

• Avoid routine urine cultures in asymptomatic patients, as asymptomatic bacteriuria does not require treatment 1, 5
• Do not perform routine toxicology screens in psychiatric patients without specific clinical suspicion 1
• Electrolyte panels ordered reflexively can lead to false positives and unnecessary follow-up 1, 6

Specimen Collection Errors

• For catheterized patients requiring urine culture, replace the catheter before specimen collection to ensure accurate results 1, 5
• Blood cultures must be drawn from different anatomical sites without time intervals between them 1
• Collect at least 60 mL total blood volume (two sets) for blood cultures to maximize yield 1

Evidence-Based Testing Strategy

The key principle is focused medical assessment based on history and physical examination rather than predetermined test batteries 1. The American College of Emergency Physicians recommends obtaining laboratory testing based on clinical findings rather than routine protocols 1.

When ordering tests, consider:

• Abnormal vital signs warrant more comprehensive evaluation 1
• Specific organ system symptoms guide targeted testing 1
• Patient age, comorbidities, and medications influence test selection 1
• Cost-effectiveness and avoiding low-yield testing improves care quality 1, 6