A blood test measures your biorhythm

Each organ its own internal clock

Medication seems to work better when people take it at a time that’s perfect just for them. That is why Roelof Hut is developing a blood test that measures people’s biorhythm. Not just their central biological clock, but also that of each individual organ.
By Laura Nederveen / Translation by Sarah van Steenderen

It might just become the new standard in medicine: a doctor takes blood from a patient and can tell within a few minutes the exact time a patient should take certain medication to ensure maximum effectiveness and a minimum of side effects.

How the body functions varies from moment to moment and from person to person. This is what’s known as the biological clock. One person might jump out of bed in the morning, while someone else needs ten different alarms just to get up. This clock, which is a lump of cells located right where the optic nerves intersect and enter the brain, not only determines people’s sleep pattern, but also their appetite, body temperature, and libido.

‘The body has this central biological clock, but each organ has its own rhythm’, says chronobiologist Roelof Hut in his office at the Linnaeusborg. The liver, for example, can be two hours ahead of the central clock, while the kidneys might just lag an hour behind.

Local clocks

Hut and his team are working on a method to measure the ‘time’ on those clocks, through a blood test. This is because the local clocks influence how nutrients and medication are absorbed. Most medications need to be taken before a meal, because people’s intestines are more active and will therefore be more absorbent. But how the body responds to the medication depends on people’s biological clocks.

‘A colleague of mine used this information in his own life’, says Hut. The man had an issue with his retina and he’d been prescribed an antipyretic that he had to take three times a day. ‘By timing it exactly right, he only needed to take one pill a day.’

By timing it exactly right he only needed to take one pill a day

Doctors and pharmacists barely take organ clocks into account. That’s not because no one’s done any research into the best time to take medication. In fact, there’s been quite a lot of research. One particular type of chemotherapy turned out to be 25 percent more effective when administered at night instead of during the day. Studies like these are often done in groups, and the results can be unclear, says Hut. ‘That’s potentially due to the differences between the individuals.’


The blood test Hut is working on should enable individuals to take organs’ specific biorhythm into account when taking medication. Each organ produces a unique pattern of substances that are used in metabolic processes. These substances, such as amino acids, glucose, and adrenaline, are called metabolites.

Hut uses a mass spectrometer to analyse the blood sample. The analysis results in a list of metabolites. ‘We’ve been looking for patterns that could predict the clock’, he says. He’s looking for a combination of metabolites, since he needs various measuring points. ‘We’re now able to accurately tell a person’s body time to within an hour. That’s more accurate than asking people what time they go to bed, because it tells us the body’s biological time.’

Finding these patterns was a matter of trial and error: one algorithm wasn’t precise enough, and so they had to use a new method to analyse the data. By now, though, the results about the central clock are nearly ready to be published. Hut is now focusing on organs’ local clocks. ‘It’s not easy, but we’re making headway.’

Clinical trials

There’s a way to go before the blood test can actually be used in medical clinics, though. Hut expects that the biological clock affects many types of medication, but he needs to do clinical trials to research this, and trials are expensive. He doesn’t think the pharmaceutical industry would be interested in funding him: ‘We can’t patent the test, because we don’t have a new molecule or a new machine.’ Individually timing medication would also mean lower doses would suffice, and that’s not in the pharmaceutical industry’s interests.

We want to prove that medication timing works for at least one organ

Hut is hopeful nevertheless. ‘We’ll start by spreading information and improving medical protocols’, he says. This will also require clinical tests, but ‘first we want to prove for at least one organ that medication timing works, so we have proof of principle’.

The liver is an ideal candidate, since it not only processes medication but nutrients as well. It’s easier to show how local clocks work with nutrients than with medication. When a person eats at night, their cells are less sensitive to insulin. They won’t absorb the glucose as well as they should, and the body goes into a kind of pre-diabetic stage. ‘People who work night shifts would benefit from properly planning their eating moments’, says Hut.

For his research, he is collaborating with the Jeroen Bosch hospital in Den Bosch. Hut laughs. ‘The night nurses are really eager to start sticking each other with needles.’


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