Who is fighting the infection — and whether the blood can still stop itself
Two panels, one page, because they produce the two sets of precautions you will actually put up at the bedside. The differential tells you what kind of invader the body thinks it is fighting. The coagulation panel tells you whether the blood can still stop itself — and it hangs on one pairing students reverse constantly: PT/INR watches WARFARIN, aPTT watches HEPARIN.
📄 Simple Nursing original — opens in Drive →
One number for “something is happening”, one calculation for “can they defend themselves”.
Figure 2 — the total count says something is happening; the ANC says whether the client can still defend themselves. Only one of those two decides precautions.
Typical adult ≈4.5–11.0 ×10⁹/L (4,500–11,000/mm³). Many nursing texts round this to 5,000–10,000 — use the range printed on your patient’s result.
It counts all white cells together, so it tells you that something is happening. It does not tell you what. That is what the differential is for.
What it means: the client cannot fight infection. The lower it goes — and especially the lower the ANC goes — the more dangerous it is.
Causes to expect on the chart: chemotherapy, immunosuppressant drugs, radiation, HIV, lupus and other autoimmune disease, aplastic anemia, and — importantly — overwhelming sepsis, where the white cells are consumed faster than they can be made.
Priority sign: a low-grade fever. In a neutropenic client that is treated as sepsis until proven otherwise.
What it means: something is being fought — usually a bacterial infection.
Always read it with the temperature, the wound, the lungs and the urine.
ANC = total WBC × (% segs + % bands) ÷ 100.
Worked example: WBC 2,000/mm³, segs 18%, bands 4% → 2,000 × 0.22 = 440 → severe neutropenia.
Thresholds vary between facilities — follow your own policy.
In a client with HIV, the CD4 count tracks a specific lymphocyte and predicts opportunistic infection risk. A count that has fallen below about 200 cells/mm³ is the threshold usually taught as the danger line.
It answers a different question from the WBC: not “is there an infection now?” but “how defenseless is this client?”
Five cell types, and what each one rising is trying to tell you.
Figure 1 — five cells, five stories, and the maturation line that explains what a “left shift” actually is.
| Cell | Typical % | A RISE suggests |
|---|---|---|
| Neutrophils (segs) | 55–70% | BACTERIAL infection · also stress and steroids |
| Lymphocytes | 20–40% | VIRAL infection · some leukemias |
| Monocytes | 2–8% | CHRONIC infection (e.g. TB) · the recovery phase |
| Eosinophils | 1–4% | ALLERGY and PARASITES · asthma, eczema, drug reactions |
| Basophils | 0.5–1% | Allergic and inflammatory states |
Percentages are typical adult values and vary by laboratory. The five add up to 100, so one can look high only because another fell.
Neutrophils up → think BACTERIAL. Lymphocytes up → think VIRAL.
That one line answers a startling share of differential questions. Add the third: eosinophils up → allergy or parasites, and you have covered nearly all of them.
Then check the bands. If the bands are up, the marrow is under real pressure.
A left shift means immature bands are being pushed out of the marrow.
The old laboratory charts listed white cells from immature on the left to mature on the right. When the immature end of the chart fills up, the count has “shifted to the left”.
What it means clinically: a serious, usually bacterial, infection — the marrow is emptying its shelves. It can appear before the total WBC has finished climbing, and it can appear in sepsis even when the total WBC is low.
Always ask what changed since yesterday — a differential shifting is more informative than a differential sitting still.
Two arms, one common path, and two brackets you must never swap.
Figure 3 — the whole reason the pairing gets reversed is that people memorize the words without the picture. Learn the picture: aPTT brackets the LEFT arm, PT/INR brackets the RIGHT.
PT/INR watches WARFARIN. aPTT watches HEPARIN.
Never give protamine for a warfarin bleed, and never give vitamin K for a heparin bleed. Wrong antidote = no effect and lost time.
The INR exists because PT reagents differ between laboratories. The INR converts a PT into a standardized number so a result means the same thing anywhere.
Figure 4 — for a client on an anticoagulant, “normal” is the wrong target. Therapeutic is a deliberately abnormal window, and the danger zone starts above it.
These are the two numbers that make you stop and pick up the phone.
A client on warfarin with an INR of 1.1 is not reassuring — they are unprotected and still at risk of the clot the drug was prescribed for.
The same applies to an aPTT sitting at baseline on a heparin infusion. Ask “what is this client’s target?” before you decide whether a number is good.
Site, speed, test, target, antidote — five columns that keep them apart.
Figure 5 — different site, different speed, different monitoring test, different antidote. Almost every exam question about these two drugs lives somewhere in this figure.
Teaching: keep vitamin K intake steady — do not stop eating green leafy vegetables, just do not swing wildly. Report any new drug, herb or supplement; interactions are extensive.
Low-molecular-weight heparin (enoxaparin) is given subcutaneously, has a more predictable effect, and is not monitored with a routine aPTT — an anti-Xa level is used when monitoring is needed. Give it in the abdomen, at least 2 inches from the umbilicus, and do not expel the air bubble or rub the site.
Answer first: the platelet count falls, but the danger is CLOTTING, not bleeding.
Do not give platelets in HIT unless specifically ordered — it can make the clotting worse.
Aspirin, clopidogrel and similar drugs do NOT lower the platelet count. They stop the platelets you already have from sticking together.
Enoxaparin is an anticoagulant, not an antiplatelet — but it belongs on the same “bleeding risk” list at the bedside.
Every number on this page ends in one of two bundles at the bedside.
Figure 6 — the two lab results, the two sets of precautions, and the one rule that appears on both lists for opposite reasons.
Trigger: ANC under 500 (or a low WBC with a falling trend — follow your facility’s threshold).
Trigger: platelets under 50 ×10⁹/L, INR over 4, aPTT over 100 s — or any active bleeding.
Same action, two completely different reasons:
Many clients — especially on chemotherapy — have both problems at once.
Figure 7 — where bleeding actually shows itself. Work down this list every shift on any client with a low platelet count or a high INR/aPTT.
Figure 8 — the two vials, and the four steps that always come before either of them is given.
Use SBAR, and arrive with a recommendation: what you have already held, and what you think is needed.