Chemotherapy — General Principles
A client's ANC drops to 800/mm³ on day 10 after chemotherapy. Knowing when and why this nadir happens determines whether the client lives through the treatment that's supposed to save them.
Core Concept
Chemotherapy kills rapidly dividing cells — cancer cells, but also bone marrow precursors, GI mucosa, and hair follicles. The nadir is the lowest point of blood cell counts after a chemotherapy cycle, typically occurring 7–14 days post-administration depending on the agent. The absolute neutrophil count (ANC) is the critical lab: ANC = (% neutrophils + % bands) × WBC. An ANC below 1,000/mm³ is neutropenia; below 500/mm³ is severe neutropenia with high infection risk. Neutropenic precautions include private room, no fresh flowers or raw fruits/vegetables, strict hand hygiene (the single most effective intervention), no rectal temperatures or suppositories, and avoiding IM injections. The classic danger sign is fever — even low-grade (≥100.4°F / 38°C) in a neutropenic client is a medical emergency requiring immediate blood cultures and broad-spectrum antibiotics. These clients cannot mount a normal inflammatory response, so classic infection signs like redness, swelling, and purulent drainage may be absent. Fever may be the only indicator of sepsis.
Watch Out For
Don't confuse nadir (the lowest WBC/ANC point, days 7–14) with onset of side effects (nausea can start within hours). Students think a normal WBC means the client is safe, but you must calculate the ANC — a WBC of 3,000 with only 10% neutrophils gives an ANC of just 300. A neutropenic fever is treated as sepsis until proven otherwise, not watched and reassessed.
Clinical Pearl
No pus, no redness, no problem? Wrong. A neutropenic client can't make inflammation — fever alone is your fire alarm. Treat it like sepsis.
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