# A 72-year-old client with coronary artery disease is started on levothyroxine 25 mcg daily for newly diagnosed hypothyroidism. The client takes calcium carbonate with dinner and ferrous sulfate with lunch. Which instructions should the nurse include? Select exactly 3 responses.

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> subject: Adverse Effects/Contraindications/Interactions  
> category: PPT

## Question

A 72-year-old client with coronary artery disease is started on levothyroxine 25 mcg daily for newly diagnosed hypothyroidism. The client takes calcium carbonate with dinner and ferrous sulfate with lunch. Which instructions should the nurse include? Select exactly 3 responses.

Select exactly 3 responses.

1

Have the TSH level rechecked in 1 week to guide the next dose.

2

Take levothyroxine with water 30 to 60 minutes before breakfast.

3

Report new chest pain or a racing heartbeat to the provider promptly.

4

Take levothyroxine with breakfast each day so the timing stays consistent.

5

Skip the dose on any day the resting pulse is above 90 per minute.

6

Take the iron tablet at least 4 hours apart from levothyroxine.

## Explanation

Levothyroxine is absorbed best on an empty stomach, and calcium and iron bind it, so the doses must be separated by about 4 hours. Because this client is older and has coronary artery disease, therapy starts low and increases slowly; new chest pain or palpitations can signal that the dose is too much for the heart. TSH is reassessed about 6 to 8 weeks after a dose change, so a 1-week recheck is wrong. Taking it with breakfast lowers absorption, and self-skipping doses by pulse is a digoxin-style rule that does not apply.

## In-depth explanation

Quick answer
Take it on an empty stomach, keep iron (and calcium) about 4 hours apart, and report chest pain or a racing heartbeat.

Why this is correct
Food, calcium, and iron reduce levothyroxine absorption. In an older client with coronary artery disease, thyroid hormone raises myocardial oxygen demand, so dosing starts low, rises slowly, and new angina or tachycardia must be reported.

Easy analogy or mental picture
Think of the heart as an old engine: you raise the throttle a notch at a time and listen for knocking before going faster.

Memory hook
Empty stomach, four-hour gap, go slow with an old heart.

NCLEX decision rule
When a teaching item adds age, heart disease, or other medicines, the key applies those details; generic rules alone are not enough.

Why the other choices are wrong
A TSH check at 1 week ignores the 6-to-8-week steady state. Taking it with breakfast sounds like good consistency teaching, but food at breakfast cuts absorption. A pulse-based hold rule belongs to drugs such as digoxin; for levothyroxine, new tachycardia or chest pain is reported, not self-managed by skipping doses.

References
1MedlinePlus: LevothyroxineTake on an empty stomach; separate from calcium and iron; report chest pain or rapid heartbeat
2DailyMed: levothyroxine prescribing informationLower starting dose and slow titration in older adults with cardiac disease; TSH reassessed 6 to 8 weeks after a dose change

## Clinical scenario

Scenario
An older adult with coronary artery disease begins low-dose levothyroxine while taking calcium and iron supplements.

## Key concepts

- **TSH** — Thyroid-stimulating hormone; the main blood test used to adjust the levothyroxine dose after it reaches steady state.
- **Steady state** — The point, about 6 to 8 weeks after a levothyroxine change, when a lab value reflects the new dose.
- **Chelation** — Binding of a drug by minerals such as calcium or iron in the gut, which lowers absorption.

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