Tests and monitoring while you are on alpelisib

Monitoring on alpelisib focuses on two things: keeping you safe from its side effects, and checking whether the cancer remains under control. Before starting, you need a test confirming a PIK3CA mutation in the cancer. Your team also measures fasting blood sugar and HbA1c, because high blood sugar is the most common side effect, and makes sure any diabetes is well controlled first. Baseline blood tests usually include a blood count, kidney and liver function, and salts such as sodium and potassium. Women who could become pregnant have a pregnancy test, and scans record where the cancer is. During treatment, blood sugar is the most closely watched result. The official guidance recommends checking fasting sugar at least once a week for the first two weeks, then regularly after that, with HbA1c every few months, and more often if readings are high or you have diabetes. Many people also check sugar at home with a glucometer. Kidney tests and salts may be repeated after loose motions or vomiting. Your weight, skin, mouth and breathing are reviewed at clinic visits. Fulvestrant injections bring you to the clinic regularly, which is a useful time for checks. To see whether alpelisib is working, scans are usually repeated every two to three months, alongside how you feel and sometimes tumour marker blood tests.

Sugar is checked most

Frequent checks in the first weeks catch rises early.

Scans track the cancer

They are compared with your starting scan every few months.

Your symptoms matter

Report rash, loose motions, cough or thirst between tests.

Regular tests make alpelisib much safer, but they cannot catch everything.

Problems can arise between tests

Symptoms such as extreme thirst, a spreading rash or new cough need reporting, even if your last result was fine.

Trends matter more than single results

Your team looks at how numbers change over time.

Scans can be uncertain

Sometimes a repeat scan or another test is needed before a clear answer.

What this page cannot tell you

It cannot interpret your own results. Ask your team to explain your numbers and scan reports.

Review visits are short, so preparation helps you cover everything.

Bring your records

Carry your sugar log, medicines list and any notes on side effects.

Come fasting if asked

Some teams want fasting blood tests on the day. Check whether to delay your alpelisib dose and breakfast until after the test, and bring food.

Ask about results

Ask what your latest sugar, kidney tests and scans show, and whether anything needs to change.

Scheduled tests cannot catch everything. Some symptoms need a call before your next appointment.

Signs of high sugar

Extreme thirst, passing a lot of urine, blurred vision, vomiting or confusion need prompt advice or urgent care.

Skin and breathing changes

A spreading rash, blistering, sore eyes, a new cough or breathlessness should be reported the same day.

Bowel and fluid problems

Loose motions that continue despite tablets, or dizziness and very little urine, may mean you are dehydrated and need checks.