Loin refers to the side of the body below the rib cage to just above the pelvis.
Loin pain is a common presenting symptom in general. It typically comes from the kidney. The potential underlying causes for loin pain are extensive. The most common causes are renal calculi, urinary tract infection or UTI, and musculoskeletal problems.
Loin pain can either be acute or chronic. Acute loin pain may be brought about by renal calculi or obstructed infected kidney which may potentially be a life-threatening disease. Acute loin pain has associated symptoms like fever, vomiting, rigors, and lower urinary tract symptoms. Muscular pain is usually felt with movement. Chronic loin pain may possibly be caused by a renal tumor. This is often associated with a mass and visible haematuria.
Causes and Associated Symptoms of Loin Pain
There are a lot of possible causes of loin pain.
- Blood clots – can cause sudden ureteric colic and obstruction
- Chronic kidney pain
- Infected obstructed kidney
- Kidney tumors – gradual onset, painless haematuria, possible mass; most common forms are Wilm’s tumor in children and clear cell carcinoma in adults
- Loin pain haematuria syndrome – characterized by loin pain with haematuria of varying degree and no apparent cause
- Papillary necrosis – acute obstruction of the ureter from the sloughed papilla; may be caused by cirrhosis, urinary tract obstruction, sickle cell disease, tuberculosis, analgesic abuse, recurrent pyelonephritis, diabetes, and renal transplant rejection
- Pelvic-ureteric junction (PUJ) obstruction – diuresis causes dissension of the renal colic and pelvis and usually follows drinking large amounts of liquid
- Pyelonephritis – accompanied by very high temperature, vomiting, and rigors; pain is dull ache
- Renal calculus
- Renal colic – sudden onset pain, constant and persistent pain, severe, makes the individual squirm in pain; pain may expand to the anteriorly and the groin; moving stone is more painful than a static one
- Renal infarction – affects both kidneys; hematuria and unilateral flank pain; characterized by loin pain accompanied by fever, vomiting, and nausea; affects both sexes but the average age of affected patients is 65
- Renal Tumor
- Urinary tract infection (UTI)
Other Local Causes
- Dissecting abdominal aortic aneurysm – may cause loin pain that is similar to renal colic; an aneurysm can be near the ureter and may cause hematuria due to trauma or irritation
- Herpes zoster – characterized by a burning pain in a band which corresponds to a dermatome; pain high precede the rash; skin is tender
- Muscular pain/strain – produces an aching discomfort that may be caused by excessive or improper bending or lifting; affected area is most likely to be tender
- Retroperitoneal fibrosis – insidious onset, dull pain, becomes progressively severe
- Rib fracture
- Thoracic/lumbar spine nerve root pain
The pain caused by pulmonary conditions can originate from the pleura or the lung. It is usually a sharp stabbing pain.
- Pulmonary embolism
Less Common Causes
Here are the less common causes of loin pain:
- Acute nephritis
- Adrenal tumors and hemorrhage
- Berger’s disease
- Colon cancer
- Crohn’s disease
- Myocardial infection
- Polycystic kidney disease
- Renal vein thrombosis
- Splenic infarction
Diagnosing Loin Pain
Since there are a number of conditions associated with loin pain, there are also varied exams to diagnose the cause of it.
A doctor initially conducts an interview with the patient to know about the history of illnesses especially the family history of the patient. After the interview, the doctor conducts a physical exam and may recommend some tests based on the symptoms described by the patient. Renal stones are common and are commonly found in individuals with a family history.
The following questions may be asked during the assessment:
- When did the pain start?
- Was the onset gradual or sudden?
- Is the pain intermittent or continuous?
- What does the pain feel like? Is it burning, gripping, or stabbing?
- Is there vomiting or nausea?
- Are there relieving or aggravating factors?
- Is there a radiation of the pain?
- Are there other urinary symptoms? Does your urine look normal?
- Is there a history of pyrexia or rigors?
- Have you had a similar kind of pain before?
A physical examination is done to look at a patient’s general appearance.
The doctor assesses if the patient has shock, dyspnoea, or pyrexia. The patient is also observed whether he/she can lie still or writhes around. The pulse rate, blood pressure, and temperature are also taken into account.
Urine examination or urinalysis is the most common exam done since the most frequent causes of loin pain are due to renal or kidney problems. Urinalysis can show uric acid, cystine, or urinary crystals of calcium oxalate. Urinalysis is also used to look for white cells, red cells, and nitrites in the urine. Microscopy can reveal casts, pyuria with infection, and haematuria with stones. Haematuria whether microscopic or gross is seen in about 85% of renal colic.
Ultrasound reveals stones that are not more than 0.5 cm in diameter. It indicates the shape and size of the kidneys and hydronephrosis.
Helical CT scan can reveal ureteric stones which is difficult to reveal through ultrasound.
Intravenous pyelogram (IVP) shows a clear view of the whole urinary system. It exhibits mild hydronephrosis. Non-opaque stones are shown as filling defects.
Retrograde pyelogram shows the anatomy of the renal pelvis and the ureter and a diagnosis of ureteric calculus. Stones, tortuosities, kinks in the ureter, or strictures become visible.
Other exams can be done such as full abdominal examination, respiratory system examination, cardiovascular examination, and back examination.
Treatment of Loin Pain
The treatment of loin pain depends on the underlying cause. Most cases require antibiotics to be taken for a week. Analgesics, pain medicines, NSAIDs, or opiates can also be prescribed by the doctor. Medicines should only be taken with a doctor’s advice.
Some doctors may require a patient to be hospitalized for observation. If the pain does not disappear after 1 to 2 days and the patient is feverish and shows other symptoms, the patient is referred for admission. For more severe cases, a urological or surgical emergency might be called for.
For renal infarction, it is recommended to do an intra-arterial thrombolysis or an intravenous heparin.
Oral fluids are recommended to allow the passage of stones. Obstruction of infection is frequently treated by percutaneous nephrostomy.