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The kidneys are in the back, one on each side of the spine. They are about 2 inches (5cm) deep, just behind the lower ribs. Pain in a kidney is usually felt as lower back pain, on one side or the other. The pain can run down into the groin, or further down the back. The kidneys lie next to the muscles of the back, so that it can sometimes be difficult to tell the difference between muscle pain, back pain or kidney pain.


There are many causes of kidney pain. Infection in the kidney and kidney stones are common causes. X-ray tests will detect kidney stones. Samples of urine will be sent to the laboratory for culture tests to see if infection is present. Other conditions which cause some swelling or irritation of the kidneys may also cause pain, and a more rarely coined term would be loin pain-haematuria syndrome.


Loin pain-haematuria syndrome (also known as LPHS) is a combination of loin (ie kidney) pain and haematuria, which is a medical term for blood in the urine.

The loin pain may be a continuous dull ache, or intermittent, coming on only occasionally and could be from one side or both.

The blood in the urine may be visible to the naked eye, coming in occasional attacks. There may even occasionally be blood clots. In other cases, the amount of blood is so small that it cannot be seen, but is detected when the urine is tested in the clinic.


There are several conditions which can cause this problem. A kidney biopsy, or sometimes an angiogram test, is used in many people to make a clear diagnosis. The conditions are all essentially abnormalities within the tissue of the kidney. The commonly encountered explanation of loin pain-haematuria are:

  1. IgA nephropathy. This is a condition in which small amount of a type of normal antibody (called IgA) get stuck in the kidney as it passes through in the bloodstream. This is a chronic condition, which sometimes goes away on its own but occasionally can cause damage to the kidneys. A related condition called IgM nephropathy can sometimes cause pain. (Click on the following links for more information on IgA and IgM ).
  2. Thin membrane disease. In this condition the membrane that filters the blood to make urine is too thin, and blood can pass across it in very small amounts. In a few cases of this condition, there is pain in the kidneys, usually occurring in attacks every so often. Although this condition can be painful, kidney failure does not seem to occur in the long term, so that the only real problem is the symptoms.
  3. In some cases, loin pain-haematuria syndrome occurs after a bladder infection with involvement of the kidney. Even when the infection has been treated and bugs can no longer be found in the urine, pain may persist for 6 months, or even longer in some cases.
  4. ‘Nut-cracker syndrome’ is when the large main artery of the body can compress on the left kidney’s vein, interrupting blood flow. Common treatments include monitoring, stenting or surgery but not always successful at irradicating symptoms.
  5. "Classic loin pain-haematuria syndrome". Some patients have none of the above diagnoses. In these cases there may be minor abnormalities on a kidney biopsy. Angiogram tests to look at the blood vessels in the kidney may show abnormal blood flow, perhaps causing a cramp like pain. The cause is not fully understood. It certainly is commoner in women than in men, and there may be hormonal influences. Some women find the pain is worse at different times of their menstrual cycle, or comes on during pregnancy, or if they are taking the oral contraceptive.
    This condition may persist for some years, and can be lifelong. Damage to the kidneys leading to kidney failure does not occur.


If infection is suspected, a course of antibiotics may be given. Long term preventative antibiotics may be necessary in some cases.

Loin pain-haematuria syndrome may, in a few people, responds to anticoagulant treatment with warfarin or aspirin - this reduces the tendency for blood flow in the kidney to be interrupted.

In the majority of cases, however, little can be done apart from trying to ensure adequate treatment for the pain itself. The types of treatment that may be effective vary from person to person, and advice from a doctor specialising in pain relief may be needed.


Pain that will not go away easily is very unpleasant. Read more on how to cope with pain.


A joint approach from the kidney specialist, general practitioner and, if necessary, a pain specialist or psychologist may not always be enough. If you want further advice or treatment, please discuss this with your specialist.

Last reviewed September 2022
Next review September 2025

Reviewed by Dr Oshini Shivakumar 'Specialist Renal Registrar'

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The National Kidney Federation cannot accept responsibility for information provided. The above is for guidance only. Patients are advised to seek further information from their own doctor.