What is loin pain haematuria syndrome?

Loin pain haematuria syndrome (also known as LPHS) is a combination of loin (i.e. kidney) pain and haematuria, which means 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.

Typical site of kidney pain (from Edren website)

The blood in the urine may be visible to the naked eye (‘macrohaematuria’), 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 on a urinary dipstick or in the laboratory (‘microhaematuria’).

Causes of loin pain haematuria syndrome

There are several conditions which can cause this problem. A kidney biopsy, or sometimes an angiogram (x-ray of the renal (kidney) arteries), may be needed in some people to make a clear diagnosis. The conditions are all abnormalities of the tissue of the kidney.

Some doctors LPHS differentiate ‘Type 1 LPHS’ from ‘Type 2 LPHS’ (which some call ‘Classic LPHS’). In Type 1 LPHS a pathological cause can be identified, e.g. IgA nephropathy, thin membrane nephropathy and nutcracker syndrome. Cases in which diagnostic work-up does not reveal a cause have been categorised as Type 2 LPHS.

‘Type 1 LPHS’

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 form of chronic glomerulonephritis, and is usually a long term condition. They are autoimmune diseases – i.e. when the body’s immune (defence) system, starts attacking its own tissues.

IgA nephropathy sometimes goes away but can damage to the kidneys, leading to CKD (and dialysis or a kidney transplant in a few cases). A related condition called ‘IgM nephropathy’ can sometimes cause pain and haematuria.

Thin membrane nephropathy. 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 the only real problem is the symptoms.

‘Nut-cracker syndrome’. This 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 these not always successful at eradicating symptoms. It was first described by John C Boileau Grant in 1937.

Post urinary tract infection (UTI). In some cases, loin pain haematuria syndrome occurs after a UTI with involvement of the kidney (pyelonephritis). 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.

Type 2 LPHS: Classic loin pain haematuria syndrome

Key Points

Classic loin pain haematuria consists of loin or flank pain with blood in the urine
The cause of the condition is not known
It can improve with time
Loin pain haematuria does not damage the kidneys
It can be difficult to treat but strong painkillers should be avoided if possible. Surgery is not recommended.

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.

In one series of patients, average age at onset of kidney pain was 30 years, and 70% were women (Bass, 2007; 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. Endometriosis should be excluded if appropriate.

This condition may persist for some years, and can be lifelong. Damage to the kidneys leading to kidney failure does not occur.

Diagnosis

Classic LPHS is a diagnosis of exclusion. In other words, the diagnosis of classic loin pain hematuria syndrome can be made when haematuria is present, recurrent or persistent pain is severe, and other causes of bleeding have been excluded. It has the following features.

Other causes of bleeding (e.g. urinary infection, tumour, or nephrolithiasis (stones) have been excluded.
Obstruction of the urinary tract should not be present, confirmed by at least two imaging procedures while pain is present (e.g. a kidney ultrasound and CT).
Urine testing (MSU rather than dipstick) always shows microhaematuria.
Low level proteinuria can be found in some patients with LPHS.
Kidney biopsy will be normal but there may be an excess red blood cells in the kidney, characterised by dysmorphic red cells. It is used to exclude chronic glomerulonephritis (especially IgA nephropathy) and thin membrane nephropathy (characterised by a thin glomerular basement membrane).
Recurrent or persistent severe pain for six months or more, occurring in the kidney area.

What causes it?

The cause is not known. Multiple mechanisms for LPHS have been proposed, including: blood vessel disease of the kidneys (e.g spasms, or venocalyceal fistula), immune disease (e.g. complement activation or hypersensitivity), blood clotting problem (coagulopathy), abnormal ureteric peristalsis, psychopathology, and microcrystal formation in the renal tubules.

The haematuria in LPHS may be due to an abnormal (thick or thin) glomerular basement membrane. An abnormal glomerular basement membrane may allow red blood cells into the urinary space.

But in most people who have tests looking for these abnormalities, nothing is found. We know that the blood leaks into the urine within the kidney, but we do not know why the condition is so painful.

There is a suggestion that 50% of patients have a previous history of kidney stones (Spetie, 2006).

Does it harm the kidneys?

Classic LPHS was first described by Peter Little in 1967, and there have been no cases reported of the disease causing any damage to the function of the kidneys (i.e CKD).

How bad can the pain be?

Pain is the biggest problem in this condition. In some people it can be nothing other than an ache that disappears with time, but in others it can be a severe pain that comes and goes for years. Some people can be incapacitated by the pain, requiring time off work and strong painkillers.

Treatment

Loin pain haematuria syndrome may, in a few people, respond to anticoagulant treatment with warfarin or aspirin – this reduces the tendency for blood flow in the kidney to be interrupted. Angiotensin converting enzyme inhibitors are thought to be beneficial.

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. In general, opiates should be avoided.

One of the difficulties in treating this condition is that it is very variable between people who suffer it; it is not even certain if this is one condition or a group of similar diseases.

A joint approach from a kidney specialist (nephrologist), general practitioner and, if necessary, a pain specialist or psychologist may be required.

Surgical perspective

However, large retrospective UK studies of CT KUBs performed for investigation of acute kidney pain only reveal ureteric or kidney stones in only 53%, with 23% of patients having no abnormalities identified on CT KUB. Patients with persistent kidney pain and a normal CT KUB can therefore present a significant challenge to the urologist (Walker, 2020). They are usually discharged. A small number are referred on to a nephrologist, quite reasonably.

Does surgery help?

Unfortunately not. Many different types of operation have been tried to treat this condition over the years, but none have met with permanent success. Surgery sometimes gives rise to a short period without pain, but it usually returns.

If the pain is one sided, operations to remove the kidney from that side usually result in pain starting on the other side. Removal of one or both kidneys for a condition that does the kidney no harm in the long run, is not recommended.

Summary

We have described what is loin pain haematuria syndrome. We hope it has been helpful.

Other resources

Bass, 2007 described a group of patients with classic LPHS. There is a good discussion of the pros and cons or various types of medical or surgical treatment. Dube, 2006 is a review article.
A rare enzyme deficiency has been seen in one patient.
A study looking for genetic causes is underway at present.
These are 12 steps to learn to control the pain written by Professor Rob Higgins (a retired consultant nephrologist).

The article includes information from the articles above and the NKF website written by Dr Oshini Shivakumar (Renal Registrar), and the EdRen website by Dr Paddy Gibson (Consultant Nephrologist, Edinburgh Royal Infirmary)

Last Reviewed on 21 January 2024