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HLT-PHLE88-03 · Lesson 7 · 5 clock hours · lab

Point-of-Care Testing: Glucose, Hemoglobin, and Coagulation Monitoring

Objective. Students will perform a point-of-care blood glucose test using a training glucometer following the manufacturer's procedure, correctly document the result, and identify critical values that require immediate reporting.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed clinician in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it to make decisions about any patient or medication. Always follow your instructor, your supervising professional, and current official references and regulations.

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What Is Point-of-Care Testing?

Point-of-care testing (POCT) means performing a diagnostic test at or near the patient rather than sending a specimen to the central laboratory. In phlebotomy practice, the most common POCT procedures are blood glucose monitoring, hemoglobin measurement, and coagulation monitoring. Results are available in seconds to minutes, allowing care teams to act quickly. As a phlebotomy technician, you may perform POCT under the supervision of a licensed healthcare provider and within your facility's written policies.

Why Glucose Monitoring Matters

Blood glucose is the concentration of sugar in whole blood. It must stay within a narrow range for the body to function normally. Values that are too low (hypoglycemia) or too high (hyperglycemia) can cause serious harm, including loss of consciousness or death if not treated promptly. Patients with diabetes, those receiving intravenous nutrition, or critically ill patients may require glucose checks several times per day.

A point-of-care glucometer uses a small drop of capillary whole blood applied to a disposable test strip. An electrochemical reaction on the strip produces a signal that the meter converts to a glucose reading, typically reported in milligrams per deciliter (mg/dL) in the United States.

Hemoglobin and Coagulation POCT

Point-of-care hemoglobin analyzers (such as the HemoCue) measure hemoglobin concentration from a capillary or venous sample. They are used to quickly identify anemia before procedures or blood donation. Coagulation monitors such as the CoaguChek measure the INR (International Normalized Ratio) from a fingerstick, helping providers manage patients on anticoagulant therapy. The same principles of quality control, documentation, and critical-value reporting apply to all three test types.

Quality Control: The Non-Negotiable First Step

Before testing any patient specimen, you must run quality control (QC) solutions. QC solutions contain a known concentration of analyte. Manufacturers supply at least two levels — a low control and a high control — with an acceptable target range printed on the control solution packaging or the lot-specific insert.

Steps to run QC:

1. Check that the glucometer code or test strip lot number matches the strip container (some meters require this).

2. Apply the low control solution to a test strip exactly as you would a patient sample.

3. Read and record the result on the QC log (date, time, lot number, control level, result, acceptable range, pass/fail, your initials).

4. Repeat with the high control solution.

5. If either result falls outside the acceptable range, do not test patients. Troubleshoot per the manufacturer's instructions (check strip expiration, storage conditions, meter function), then rerun controls. Notify your supervisor.

Failing to document QC or running patient tests when controls are out of range violates Clinical Laboratory Improvement Amendments (CLIA) requirements and puts patients at risk.

Performing the Fingerstick and Glucometer Test

1. Verify the patient's identity using at least two identifiers (name and date of birth, or name and medical record number).

2. Wash hands and don gloves.

3. Select an appropriate fingertip site — the lateral (side) aspect of the middle or ring finger is preferred; avoid the thumb, index finger, and little finger. Warm the site if circulation is poor.

4. Clean the site with an alcohol prep pad and allow it to air-dry completely. Residual alcohol can alter the result.

5. Using a safety lancet, puncture the site with a single, confident motion. Wipe away the first drop of blood (it contains excess tissue fluid).

6. Gently squeeze to form a rounded second drop. Do not milk the finger aggressively — this dilutes the sample with tissue fluid and produces a falsely low result.

7. Touch the drop to the designated area on the test strip without scraping or smearing. The meter will beep or display a fill indicator when sufficient volume is detected.

8. Read the result displayed on the meter screen. Note the unit (mg/dL).

9. Apply light pressure to the puncture site until bleeding stops; bandage if appropriate.

10. Dispose of the lancet immediately in a sharps container. Remove gloves, wash hands.

Documenting the Result

A complete POCT log entry must include: patient name (or ID), date, time, test performed, result with units, reference range, whether the result is normal or abnormal, the meter ID or serial number, and the operator's name or initials. Incomplete documentation is a patient safety issue and a compliance failure.

Reference Ranges and Critical Values

Reference ranges vary slightly by facility and meter. A commonly cited general reference for fasting plasma glucose is 70–99 mg/dL. Point-of-care meters measure whole blood, so results may differ slightly from plasma values. Always use the reference range your facility or instructor provides.

Critical values are results so far outside the normal range that they represent an immediate threat to life. Common critical glucose thresholds (exact numbers vary by facility) are often set at very low values (for example, below approximately 40–50 mg/dL) or very high values (for example, above approximately 400–500 mg/dL). When you obtain a critical value:

1. Repeat the test to confirm (per facility policy).

2. Notify the responsible licensed provider immediately — do not wait, do not leave a message and walk away.

3. Use a verbal read-back: state the patient name, the result and units, and ask the nurse or provider to repeat the value back to you.

4. Document the time of notification, the name of the person notified, and that read-back was confirmed.

Safety Summary

Key terms9

Point-of-care testing (POCT)Diagnostic testing performed at or near the patient site rather than in a central laboratory, providing rapid results to support immediate clinical decisions.
GlucometerA handheld electronic device that measures the concentration of glucose in a small drop of whole blood using an electrochemical test strip.
Quality control (QC)The process of running solutions with known analyte concentrations through a testing device to verify the device is performing accurately before patient testing.
Critical valueA test result so far outside the normal range that it signals an immediate life-threatening condition requiring urgent notification of the responsible provider.
mg/dLMilligrams per deciliter; the standard unit used in the United States to report blood glucose concentration from point-of-care meters.
INR (International Normalized Ratio)A standardized calculation derived from the prothrombin time test used to monitor patients on anticoagulant therapy; can be measured at the point of care from a fingerstick sample.
Verbal read-backA communication safety technique in which the person receiving critical information repeats it back to the sender to confirm accuracy before any action is taken.
HypoglycemiaAn abnormally low blood glucose level that can cause symptoms ranging from shakiness and confusion to loss of consciousness; requires prompt medical intervention.
QC logA written or electronic record of each quality control run, including the date, time, control lot number, expected range, actual result, and pass/fail determination.

Worked examples4

1. A glucometer displays a glucose result of 312 mg/dL. The facility's critical high threshold is 400 mg/dL and critical low threshold is 50 mg/dL. Is this a critical value?
  1. Identify the result: 312 mg/dL.
  2. Compare to the critical low threshold: 312 mg/dL is greater than 50 mg/dL, so it is not critically low.
  3. Compare to the critical high threshold: 312 mg/dL is less than 400 mg/dL, so it is not critically high.
  4. Determine whether the result is within the normal reference range (70–99 mg/dL fasting): 312 mg/dL is above normal, making it a high (abnormal) result.
  5. Conclusion: the result is elevated and abnormal but does not meet this facility's critical value threshold. Document the result and report it to the provider according to routine abnormal-result policy.
Answer: 312 mg/dL is an abnormal (high) result but does not reach the critical high threshold of 400 mg/dL at this facility. It requires provider notification per routine policy, not an emergency critical-value call.
2. The low QC control solution has an acceptable range of 55–75 mg/dL. The technician runs the control and the meter displays 48 mg/dL. What should the technician do?
  1. Compare the result (48 mg/dL) to the acceptable range (55–75 mg/dL).
  2. 48 mg/dL is below 55 mg/dL, so the control is OUT of range — this is a QC failure.
  3. Do not perform any patient testing until the problem is resolved.
  4. Troubleshoot: check that the test strips are not expired, have been stored correctly, and that the strip lot number matches the meter setting. Check the control solution expiration date.
  5. Rerun the low control after troubleshooting.
  6. If the control still fails, remove the meter from service and notify the supervisor.
Answer: The low control result of 48 mg/dL is outside the acceptable range of 55–75 mg/dL. Patient testing must be halted, troubleshooting performed, the control rerun, and a supervisor notified if the problem cannot be resolved.
3. A technician performs a fingerstick glucose on a patient. The meter reads 'E-3' (error code) instead of a numeric result. The strip is not expired, the meter code matches, and controls passed earlier in the shift. The technician suspects insufficient sample volume. How should the technician proceed?
  1. Do not record the error code as a patient result.
  2. Discard the used strip in a biohazard waste container.
  3. Prepare a new test strip.
  4. Re-puncture the patient's finger (using a new safety lancet at a fresh site) or gently re-squeeze the existing puncture if bleeding has not stopped, to produce a larger second drop.
  5. Wipe away the first drop again, allow a full, rounded drop to form, then apply it to the new strip without smearing.
  6. Read and document the numeric result if the meter accepts the sample; if another error occurs, consult the manufacturer's troubleshooting guide and notify the supervisor.
Answer: The technician should discard the strip, obtain a new adequate drop of blood from a fresh fingerstick using a new lancet, and retest with a new strip, following facility policy for error documentation.
4. At 0830, a technician obtains a fingerstick glucose of 38 mg/dL on a patient named J. Rivera (the facility's critical low threshold is 50 mg/dL). The technician calls the unit nurse, states the result, and the nurse repeats it back correctly. What must the technician document?
  1. Record the patient name (J. Rivera) on the POCT log.
  2. Record the date (today's date) and time of the test (0830).
  3. Record the glucose result: 38 mg/dL.
  4. Mark the result as critically low (below the 50 mg/dL critical threshold).
  5. Record the time the critical value was reported to the nurse.
  6. Record the name of the nurse who was notified.
  7. Record that verbal read-back was performed and the nurse confirmed the value correctly.
  8. Record the technician's own name or initials as the operator.
Answer: The complete POCT log entry must include: patient name, date, test time (0830), result (38 mg/dL), unit (mg/dL), critical-low flag, time of critical-value notification, name of nurse notified, confirmation that read-back occurred, and the technician's identifying information.
In class: Glucometer quality control exercise: students run a high and low control solution on a training glucometer, record results on a QC log sheet, and determine whether the controls are in range before performing a patient simulation test. · Patient simulation: student collects a fingerstick specimen from a training model, applies the correct volume to the glucometer test strip, reads the result, documents the simulated patient name, date, time, result, and unit designation on a point-of-care log, then identifies the result as normal, low, or critically low/high using a provided reference range sheet. · Critical value role-play: instructor announces a simulated critical glucose result; student practices the verbal read-back notification script to a 'nurse' (played by a classmate), demonstrating correct professional communication and documentation of the notification.
Materials: Training glucometers with control solutions, glucometer test strips, fingerstick training models, safety lancets, gloves, point-of-care log forms, reference range sheet, phlebotomy textbook
Check: QC log completed accurately; patient simulation result documented with all required fields; critical value communication role-play rated satisfactory on a 5-item rubric; minimum 80% overall.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Safety and Infection Control / Specimen Collection
1. Before performing a point-of-care glucose test on a patient, the technician must first:
Specimen Collection
2. When collecting a fingerstick blood sample for glucose testing, the first drop of blood should be:
Patient Communication and Safety
3. A point-of-care glucose result meets the facility's critical low threshold. After confirming the result, the phlebotomy technician's next action should be to:
Specimen Collection
4. Which site is preferred for an adult fingerstick glucose collection?
Laboratory Operations / Quality Assurance
5. A QC control solution has an acceptable range of 90–110 mg/dL. The technician records a result of 115 mg/dL. What is the correct next step?
Specimen Collection / Laboratory Operations
6. In point-of-care glucose testing, the result is reported in the United States in which unit?
Specimen Collection
7. Which of the following actions during fingerstick collection can produce a falsely LOW glucose result?
Patient Communication and Safety / Documentation
8. After verbally reporting a critical glucose value to the nurse, the phlebotomy technician must document which of the following in the point-of-care log?
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