10.3 Point-of-Care and Waived Chemistry Testing

AMT III.5.C is short and binding: know that point-of-care tests are within the laboratory assistant's scope of practice, and perform point-of-care and waived clinical chemistry tests. Sections 10.1–10.2 taught the words and the devices. This section is the patient test: glucose meters, waived A1c, waived lipids, waived electrolytes when they are truly waived, plus the operational traps that make a waived result invalid. Urine chemistry dipsticks overlap Chapter 14; mention them only so you do not confuse a urine glucose pad with a blood glucose meter.

Quick Answer: After patient identification and operator competency, confirm the meter is not lockout-blocked, confirm strip lot coding, collect the IFU specimen (often capillary or venous whole blood), run the test, and treat critical hypoglycemia or hyperglycemia as report immediately. Do not share operator IDs, do not mismatch strip lots, and do not treat capillary and venous glucose as automatically identical.

POC is in scope — high-complexity chemistry still is not

Point-of-care (POC) testing is laboratory testing performed near the patient rather than on the core-lab analyzer. Many POC chemistry methods are waived; some POC cartridges are moderate complexity. CMLA performance follows the FDA classification and the laboratory's CLIA certificate, not the fact that the device is small. A handheld cartridge that is moderate complexity is not waived just because it sits on a nursing unit.

You do perform unmodified waived/POC chemistry listed in the SOP after competency. You do not independently run the core-lab chemistry analyzer, dilute a waived specimen to "make it read," or use an unapproved specimen type (Chapter 5). Off-label use still defaults the method to high complexity.

Scenario. A clinic owns a waived glucose meter and a moderate-complexity cartridge system that measures electrolytes. The CMLA performs the glucose per IFU. The CMLA does not independently run the moderate-complexity cartridge unless the laboratory's certificate, personnel rules, and SOP assign that method to an eligible testing person — a CMLA credential alone does not convert complexity.

Operator lockout, competency, and strip coding

Modern meters enforce policy that humans used to skip.

Operator lockout prevents patient testing when QC is overdue, when the operator ID is not certified on that device, or when a critical-error flag is uncleared. Lockout is a safety feature. Bypassing it by borrowing a coworker's barcode, typing a universal code taped to the wall, or switching to "training mode" for a real patient is a reportable failure. Complete QC, complete competency, or use a backup in-control meter under your own valid ID.

Strip or cartridge coding ties the lot's calibration curve to the meter. Some lots use a chip, a barcode on the vial, or a no-code system that still requires you to confirm the vial and meter match. Loading Lot A strips while the meter is coded for Lot B is an IFU failure. It can produce a tight cluster of wrong answers (precise but not accurate — Chapter 4) and is modified use if you ignore the coding step the insert requires.

Store strips in the original vial, cap closed, at the labeled temperature. Do not pour strips into a pocket, a glove, or a plastic cup. Do not use strips that were left open overnight or that expired yesterday "just this once."

Capillary versus venous glucose

Glucose is the highest-volume waived chemistry test and the easiest specimen-type trap.

• Capillary (fingerstick) whole blood is what most handheld meters are cleared for. The IFU may exclude neonates, critically ill patients, or arterial/line draws. Those exclusions are population/specimen limitations (Chapter 5), not suggestions.
• Venous whole blood may be allowed on some meters; serum or plasma poured from a centrifuged tube is not a capillary drop. Hematocrit and matrix effects change the reading.
• Capillary and venous glucose are not automatically identical. After a meal, capillary glucose is often higher than a simultaneous venous plasma glucose. Fasting values are closer. Report the specimen type the SOP requires ("fingerstick whole blood," "venous whole blood") so the clinician does not treat a POC number as a core-lab plasma glucose without context.
• Do not alternate sites (forearm versus fingertip) unless the IFU allows it; some alternative sites lag true fingertip changes during rapid hypo- or hyperglycemia.

Scenario. A patient finished breakfast. A fingerstick meter reads 180 mg/dL; a venous plasma glucose drawn minutes later is lower. That discrepancy can be physiologic, not a broken meter. You still report each result with its specimen type. You do not "correct" the meter by pouring SST serum onto the strip to match the lab.

Critical hypoglycemia and hyperglycemia: report immediately

A critical value (panic value) is a result so far from expected that it may indicate a life-threatening state. Glucose is the chemistry analyte you will see at the chair. Hypoglycemia (low glucose) and hyperglycemia (high glucose) at the laboratory's posted thresholds are report-immediately results (Work Area IV.12.G; Chapter 17).

AMT does not publish a numeric glucose panic list. Use the laboratory's critical-value table. Example facility lists often treat glucose below about 50 mg/dL, or above about 400–500 mg/dL, as critical in adults — those figures are examples, not AMT cutoffs, and pediatric or neonatal lists differ. Some meters display HI/LO instead of a number when the result is outside the reportable range; that is still a critical-path result, not a shrug.

When the meter shows a critical or HI/LO glucose:

1. Do not hide the result or rerun until a "nicer" number appears unless the SOP requires a documented repeat on a new strip with a valid reason (for example an underfilled strip error).
2. Notify the authorized provider immediately by the SOP route (in person or telephone, not a sticky note).
3. Document who was notified, the time, the result, the specimen type, and read-back.
4. Follow any SOP for a confirmatory laboratory glucose — that confirmation does not delay the first notification.

Symptoms (sweating, confusion, unresponsiveness for hypo; extreme thirst or Kussmaul breathing for severe hyper) reinforce urgency but are not required before you notify. The number is enough.

Waived A1c and waived lipids rarely produce the same minute-to-minute panic as glucose, but they still follow lockout, coding, dating, fasting (if required), and intended-use rules. A waived A1c IFU that says monitoring is not a license to diagnose diabetes off-label.

Exam traps

• Believing POC chemistry is outside CMLA scope.
• Sharing an operator ID to clear lockout.
• Mismatched strip lot coding.
• Treating capillary and venous glucose as the same specimen.
• Pouring serum onto a whole-blood glucose strip.
• Charting a critical glucose without immediate notification.
• Reporting a urine dipstick glucose as a blood chemistry glucose.

Perform the waived test the insert describes, on the specimen it names, under your own competency, and move critical glucose the same hour you see it.