Hair and skin health
Itchy Skin With No Rash: Which Blood Tests Are Worth Checking
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed September 20266 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
QUICK ANSWER
For itching all over with no rash, the usual first bloods are ferritin, thyroid function, liver markers and kidney markers, plus a full blood count. The NHS says itchy skin can less commonly point to thyroid, liver or kidney problems. Iron is the other common one worth ruling out.
Not sure which markers you need? Build your test →An itch you can see the cause of is easy. Dry skin, a bite, a patch of eczema. An itch with nothing to see is the one that keeps people up, and scratching at night without a mark on you is a different problem from a rash.
It is also common. A population study of 2,540 adults put the point prevalence of chronic itch at 13.5 per cent, so roughly one adult in seven is itching at any given time.
1. When does an itch come from inside?
Most itching starts on the skin. Sometimes it does not. The NHS puts it plainly:
“Less commonly, itchy skin can be a sign of a more serious condition, such as thyroid, liver or kidney problems.”
NHS, Itchy skin
That sentence is why a GP reaches for blood tests. On the same page the NHS notes they might arrange a blood test to help find the cause. Three of the organs it names are readable from a blood sample.
Iron is the fourth thing worth ruling out, and the NHS lists feeling itchy among the less common symptoms of iron deficiency anaemia. It sits in the same list as hair loss, a sore tongue and restless legs. If two or three of those ring true at once, iron is worth a look.
None of this means an itch is a warning sign. Most itching is skin, weather and soap. It means a persistent itch with nothing to see has a short list of things worth checking, and the list is cheap to work through.
2. Which markers are worth checking?
These are the ones that get ordered for widespread itch, and what each is actually measuring.
| Marker | What it measures | Why it is on the list |
|---|---|---|
| Ferritin | The protein that holds iron in reserve, so it shows how much iron you have banked | Itching is on the NHS list of less common iron deficiency symptoms |
| TSH and Free T4 | The signal your brain sends the thyroid, and the main hormone it sends back | Thyroid is first on the NHS list, and dry skin is a listed symptom |
| ALP and ALT | Two liver enzymes. ALP tracks the bile drainage side, ALT the liver cells themselves | Liver is second on the NHS list, and ALP is the marker of the two that leans biliary |
| Urea, creatinine, eGFR | Two waste products your kidneys clear, and a calculated score for how fast they clear them | Kidney is third on the NHS list |
| Full blood count | The numbers and sizes of your red cells, white cells and platelets | The standard first test alongside the four above |
The pattern matters more than any single row. A raised ALP on its own is a good example, because it is as often bone or vitamin D as it is liver. A low ferritin with a normal haemoglobin is another common one, and it still counts. Our guide to the full blood count covers what that test adds.
3. When do you need a GP, not a blood test?
Some itching should go straight to a doctor. The NHS says to see a GP if your itchy skin:
- is affecting your daily life
- does not get better with self care, or keeps coming back
- comes with a new rash, lump or swelling you are worried about
- is all over your body
- is severe
- happens during pregnancy
Itching in pregnancy is the one to take seriously fastest. It can be a sign of a liver condition that needs monitoring, so it is a call to your midwife or GP rather than something to test at home.
A home blood test is useful for the ordinary version of this. Itching that has dragged on for weeks, nothing to see, and nobody has checked your bloods in years. It is not the right tool for a new lump, a spreading rash or an itch that arrived with weight loss.
4. Which of these does Helvy measure?
Four of the five. The Thyroid & Vital Organs panel carries TSH, Free T4 and Free T3 alongside ALP, ALT, albumin, urea, creatinine and eGFR. That is the thyroid, liver and kidney side of the list in one finger-prick kit, for £159.
Iron sits in a different panel. Vitamins & Minerals carries ferritin with serum iron, transferrin saturation and TIBC, plus B12, folate, vitamin D and magnesium, also £159. If iron is your main suspicion, start there. Our ferritin guide explains why one reading rarely settles it.
The honest limit is the fifth row. No Helvy panel includes a full blood count, so if that is the test you want, your GP is the route. We also do not test bile acids or allergy antibodies, which are the other two people ask about for itching.
A blood test measures markers. It does not diagnose the cause of an itch, and a clean set of results does not rule out a skin condition that needs looking at. What it does is narrow the list. If you are unsure which panel fits, the build-my-test tool takes about a minute. Samples are processed by UKAS-accredited UK labs.
READY TO TEST?
Check the four things behind an unexplained itch
Helvy's home blood tests report your thyroid, liver, kidney and iron markers with the context a printout leaves out, so a figure near the edge of a range never sparks a needless panic.
Frequently asked questions
What blood tests are done for itchy skin?
The usual first set is a full blood count, ferritin, thyroid function, liver markers and kidney markers. The NHS names thyroid, liver and kidney problems as less common causes of itchy skin, which is why those three get checked together.
Can low iron make you itch?
The NHS lists feeling itchy among the less common symptoms of iron deficiency anaemia, alongside hair loss, a sore tongue and restless legs. Ferritin is the marker that shows your iron stores.
Why am I itchy all over with no rash?
Dry skin and soap are the common answers. When it lasts weeks with nothing to see, iron, thyroid, liver and kidney markers are the short list worth checking. The NHS also says to see a GP if the itch is all over your body.
Can a thyroid problem cause itching?
Thyroid is the first condition the NHS names on its itchy skin page. Its underactive thyroid page also lists dry skin as a symptom. TSH and Free T4 are the two markers that read thyroid function.
Does itching mean liver trouble?
Usually not. Liver is on the NHS list of less common causes, so it is worth checking rather than worth assuming. ALP and ALT are the two liver enzymes normally read first.
How common is long-term itching?
A study of 2,540 adults found a point prevalence of 13.5 per cent, and a lifetime prevalence of 22 per cent. It is a common complaint rather than a rare one.
Does Helvy test for allergies?
No. We do not test allergy antibodies or bile acids. Our panels cover the thyroid, liver, kidney and iron markers on this list, and a full blood count needs your GP.
Should I get tested if I am itchy in pregnancy?
Speak to your midwife or GP first. The NHS lists itching in pregnancy as a reason to see a GP, and it is not something to work through with a home test.
Related guides
Related panels
Keep reading