Why reporting comes before the dose
This client is in the third week of pelvic radiation with weekly cisplatin, and she now has five loose stools a day for 3 days. The diarrhea itself is an expected effect of radiation enteritis, but the data show that it has gone beyond a comfort problem. She has an orthostatic drop in blood pressure (from 104/68 lying to 88/60 mmHg standing, against a baseline of 118/76), a urine output of 90 mL in 4 hours (about 22 mL/h), and a serum creatinine that rose from 0.8 to 1.5 mg/dL in a week. Together these findings describe fluid volume deficit with acute kidney injury, and the next scheduled drug is a nephrotoxic one. The nurse therefore reports the fluid loss and the creatinine to the prescriber before the cisplatin is hung.
Mechanism: why cisplatin and dehydration do not mix
Cisplatin is a platinum chemotherapy drug that is cleared by the kidneys and is directly toxic to the renal tubules. For this reason it is given only with good hydration and after kidney function has been checked; the dose may be delayed, reduced, or changed when the creatinine rises. In a client who is already volume depleted, renal blood flow falls, the drug concentrates in the tubules, and injury that is still reversible can become established. A nearly doubled creatinine with low urine output is exactly the warning sign that makes the prescriber reconsider the dose. The nurse does not decide whether cisplatin is cancelled, but must make sure the prescriber sees the data before the drug is given.
Why the other actions come later
Loperamide and a low-residue, low-lactose diet are reasonable parts of managing radiation enteritis, and fluid teaching will be needed. However, waiting 4 hours to recheck after an antidiarrheal, or spending the time on teaching, leaves a nephrotoxic dose on schedule while kidney injury is developing. Blood cultures are not indicated: her temperature is 37.2 °C and her absolute neutrophil count is 1,900/mm³, so she does not meet the criteria for neutropenic fever. These options are not wrong in themselves; they are wrong as the first action.
| Finding | Value | What it means |
|---|
| Orthostatic BP | 104/68 lying, 88/60 standing | Intravascular volume deficit |
| Urine output | 90 mL in 4 h (about 22 mL/h) | Below the usual 30 mL/h minimum |
| Creatinine | 0.8 to 1.5 mg/dL in 1 week | Acute kidney injury |
| Temperature / ANC | 37.2 °C / 1,900/mm³ | No neutropenic fever |
Watch out! In chemoradiation questions, look at what is due next. A routine weekly dose becomes a safety issue when kidney function, blood counts, or hydration status change, and the nurse's role is to hold the dose until the prescriber has reviewed the new data.
Exam takeaway
When diarrhea, vomiting, or poor intake occurs in a client on a nephrotoxic drug, connect the fluid loss to kidney function. Key point! Orthostatic hypotension, low urine output, and a rising creatinine are reported before cisplatin; symptom relief, diet teaching, and infection workup follow according to the actual findings.