The repeat prescription keeps arriving whether or not the blood test happened. Nobody owns the interval, so it lapses — and the medicine goes on being taken as though somebody were still watching.

What you take, and what is already owed

Nothing is saved and nothing leaves the page. Tick from the boxes on the shelf rather than from memory if you can — the generic name is on the label. If you are ill right now with vomiting or diarrhoea, the first questions cover that.

Why it lapses, which is nobody's fault in particular

• The prescription and the test are on separate rails. The repeat is issued by a system that counts tablets; the monitoring lives in a different system that counts appointments. In most places nothing stops the first when the second is overdue, and the patient is the only person who sees both.
• The annual review is not the blood test. A medication review is a conversation; the monitoring is a sample. People come out of a review believing everything has been checked, and the tube was never taken.
• The test that was arranged and never happened. A form issued and not used, a cancelled clinic, a phlebotomy appointment moved twice, a hospital test the practice never saw. Each of these leaves a record saying it was ordered, which reads like a record saying it was done.
• Moving practice, hospital or country resets the memory. Records travel badly and monitoring history travels worst, because it is a series of dates rather than a diagnosis. After a move, assume nothing carried over and ask.
• The medicine that started in hospital. Somebody in a specialist clinic began it with a plan for monitoring that lived in that clinic's letter, and the letter is the only place the plan exists. If the clinic discharged you, the plan needs a new owner and usually does not get one.
• Nothing feels wrong, which is the design. These checks exist precisely because the problems they find are silent at the stage where they are easy to fix — a kidney sliding, a marrow struggling, a thyroid drifting, a level creeping. Feeling well is not evidence the check is unnecessary; it is what the check is protecting.

What each check is actually looking for

• Kidney function and the two salts. Blood pressure tablets, water tablets and spironolactone all move potassium and sodium, and the kidney they run through changes with age, illness and dehydration. A rising potassium is dangerous and completely silent, and it is found on a test that costs almost nothing.
• A blood count. Methotrexate and azathioprine work by holding back a fast-dividing system, and the marrow is one. The count is the check that finds the rare reaction while it is still a number rather than an infection, and it is why these medicines are safe when they are monitored.
• Liver tests. A drug irritating a liver has no symptoms until well past the point at which stopping would have been simple. This is one blood tube and it is the whole justification for the schedule.
• A drug level. Lithium has a narrow gap between the amount that works and the amount that harms, and how much is in the blood depends on the dose, the kidneys, the salt in the diet, a hot week and any new medicine. The level is not a formality; it is the only way to know where somebody is in that gap.
• Thyroid function. The dose that fitted five years ago drifts, and amiodarone pushes it in either direction. It is a slow change that reads as ageing, tiredness or low mood until somebody measures it.
• The rest of the list. Calcium after years of lithium; B12 after years of metformin; urate to check the gout dose is actually low enough to work; glucose and cholesterol on antipsychotics, where the metabolic side effects are treatable once they are found. None of these is exotic and all of them are ordinary blood.

The moments that reset the clock, whatever the interval said

• A dose change. Anything that moves a dose usually needs a check one to two weeks later rather than at the next annual slot — and a levothyroxine change needs its thyroid test at six to eight weeks, not before, because earlier is uninterpretable.
• A new medicine, including one bought over a counter. Anti-inflammatories with a blood pressure tablet and a water tablet are the classic combination that lands people in hospital; so are a new antibiotic with warfarin, and anything diuretic-like with lithium.
• Vomiting or diarrhoea, or a day too hot to drink enough. Dehydration is where a stable combination becomes an unstable one within a day or two. Several medicines have explicit sick-day rules — ask which of yours to pause and for how long, and get that written down before you need it.
• Pregnancy, or planning it. Some of these medicines need changing before conception rather than after a test result, and the monitoring changes as well. This is a specialist conversation and it is worth starting early rather than at the twelve-week scan.
• A new prescriber who does not have the history. A locum, an out-of-hours doctor, a hospital team, a private clinic. Each may add something reasonable that interacts with what is already there, and none of them holds the monitoring schedule.
• Getting older on the same dose. Kidney function falls slowly with age in everybody, so a dose that was right at sixty can be too much at eighty without anything being changed. That is the quiet version, and the interval is what catches it.

How to ask, in one sentence

• Ask for the monitoring bloods by name and say which medicines they are for. "I take lithium and ramipril; my last blood test was over a year ago — can I have the lithium level, kidney function and thyroid, please?" That sentence books itself. A request to "check my bloods" often does not.
• Ask for the dates and the numbers, not a reassurance. You are entitled to your own results in every European system. The dates matter more than the values, because a date tells you whether the schedule is being kept and a value on its own does not.
• Ask who owns the schedule for each medicine. The practice, a hospital clinic, or a shared arrangement — and if the answer is unclear, that is the finding. Somebody has to be named, or the interval belongs to nobody again next year.
• Ask for the sick-day rules in writing. Which tablets to pause if you cannot keep fluids down, for how long, and when to restart. This is a small card that prevents a hospital admission and almost nobody has one.
• Ask what happens if a result is out of range. Whether they will ring you, what number to expect, and what you should do while waiting. "We only call if there is a problem" is a system that fails silently when a result is filed unseen.
• If the answer is no, ask what would change it. A pharmacist can often see the record and start the process; a written request is harder to lose than a phone call; and the words "this medicine has a monitoring requirement I think is overdue" move a conversation that "can I have a blood test" does not.

What people believe, and what is so

The drill: 16 repeat prescriptions

Sixteen ordinary shelves — the lithium that has not had a level in fourteen months, the methotrexate taken daily instead of weekly, the ramipril through a week of vomiting, the test form in a kitchen drawer. Each has a reasonable-sounding move that leaves the interval owned by nobody. Pick the one that closes it; every answer explains why.

The card

Print it, fill it in once, and keep it with the repeat slip. It turns a vague request into a booking.

🖨️ Print the card