Fasting Before Parathyroid Surgery (Parathyroidectomy)

Fasting for this procedure

This operation is almost always done under a general anaesthetic, so you will be fully asleep and you do need to fast. As an adult, stop eating solid food, milk and milky drinks about 6 hours before your arrival time, and you may keep sipping clear fluids (water, black tea or coffee, clear apple juice, squash without bits) until 2 hours before. Do not chew gum or suck sweets inside that 2-hour window, as they make your stomach produce fluid. Some surgeons use a localised technique with sedation rather than a full general anaesthetic, but the safe approach is the same, so follow the exact timings your hospital gives you. For children having a parathyroidectomy, the timings differ (food and formula 6 hours, breast milk 4 hours, clear fluids 2 hours) and are explained on our child fasting calculator.

Medicines to check

Take your morning tablets with a small sip of water unless your pre-assessment team has told you to leave a specific one out.

Blood thinners (warfarin, apixaban, rivaroxaban, clopidogrel and similar) often need to be paused before neck surgery to reduce bleeding around the windpipe; never stop them on your own, check our guide on medications to stop before surgery.

If you have diabetes, your tablets and insulin usually need adjusting on the fasting day, so read diabetes tablets before surgery and follow your team's plan.

If you already take calcium or vitamin D supplements, ask whether to continue them, as your levels will be watched closely after the gland is removed.

Bring any recent calcium, PTH or vitamin D results and a list of all your medicines, including anything bought over the counter or herbal.

Avoid alcohol for 24 hours before your operation, as it irritates the stomach and can interact with the anaesthetic.

When this surgery may be delayed

You ate or drank inside the fasting window, even a biscuit or a milky coffee, so your stomach is not empty and the anaesthetic is unsafe.

Your blood calcium is dangerously high or low on the day and needs correcting first, since extreme calcium levels affect the heart rhythm during anaesthesia.

You are still taking a blood thinner that was not stopped in time, raising the risk of a neck haematoma pressing on your airway.

A chest infection, cold or sore throat is present, which is risky for a breathing-tube anaesthetic and for an operation so close to the windpipe.

The scan results that pinpoint the overactive gland are unclear, and your surgeon wants to repeat localisation imaging before operating.

Reports & documents to carry

Your neck localisation scans (sestamibi, ultrasound or 4D-CT) or a note of where they were done.

Recent blood results showing your calcium, PTH and vitamin D levels.

A full list of your medicines and supplements, with doses, including any blood thinners.

Your admission letter, ID and details of who is collecting you, as you cannot drive after a general anaesthetic.

Details of any past neck or thyroid surgery and any previous problems with anaesthesia.

What to ask your anesthesia team

Will my operation be under full general anaesthetic or a localised technique with sedation, and how does that change my fasting?

How will my calcium be monitored afterwards, and might I need calcium tablets when I go home?

What is the chance of a temporary voice or throat change, since nerves to the voice box run close to the glands?

Am I likely to go home the same day, or will I stay overnight for calcium checks?

Which of my regular tablets, especially blood thinners and diabetes medicines, should I stop and when?

Your prep checklist

Tick things off as you sort them — saved on this device only, nothing is sent anywhere.

A general guide — your hospital's own instructions always come first.

Frequently asked questions

Why do I have to fast if it is only a small neck operation?

Even though parathyroidectomy is a small, targeted operation, it is done under general anaesthetic, so you are fully asleep with your protective reflexes switched off. If your stomach still holds food or milk, that content can come up and spill into your lungs, causing serious pneumonia. Fasting empties the stomach. Stop solids and milky drinks about 6 hours before arrival and clear fluids 2 hours before.

Will my voice change after the surgery?

The nerves that move your voice box run very close to the parathyroid glands, just as they do in thyroid surgery, so your surgeon works carefully to protect them. A temporary hoarse or weaker voice can happen from bruising or the breathing tube and usually settles over days to weeks. Lasting voice change is uncommon. Tell your team early if your voice does not recover, as speech therapy can help.

Why is my calcium checked so closely afterwards?

Once the overactive gland is removed, the calcium-controlling system resets and your blood calcium often drops, sometimes quite quickly. Low calcium can cause tingling around the lips and fingers or muscle cramps. That is why staff take blood tests after surgery and may give you calcium or vitamin D tablets. Report any numbness, tingling or twitching promptly so your levels can be topped up safely.

Will I be able to go home the same day?

Many people having a single overactive gland removed go home the same day or after one night, because it is a small operation with a quick recovery. The main reason to stay is to confirm your calcium is stable and that there is no bleeding in the neck. Arrange for an adult to collect you and stay overnight, since you must not drive or be alone straight after a general anaesthetic.