Causes of Kidney Pain

Kidney pain can arise from various conditions, including the following:

Kidney Infection

A kidney infection, also known as pyelonephritis, is a painful condition that occurs when bacteria reach the kidneys. The most common cause of kidney infections is cystitis, which starts when bacteria enter the urethra, the tube that carries urine out of the body. Typically, these bacteria are of the Escherichia coli (E. coli) type, which migrate to the bladder, resulting in cystitis. If these bacteria travel from the bladder to one or both kidneys, the result is a kidney infection. It is important to note that kidney infections can sometimes occur without a prior bladder infection, particularly in cases involving kidney stones, diabetes, or a weakened immune system. Notably, E. coli naturally resides in the human intestines without causing harm; however, it can spread to the genital area due to improper wiping after using the restroom or during sexual activity. Furthermore, kidney infections are more prevalent in women due to their shorter urethras, allowing infections to reach the kidneys more easily. Prompt treatment is crucial to prevent potential complications, often involving antibiotics and pain relievers to manage symptoms.

Kidney Stones

Kidney stones, or urolithiasis, can form in any part of the urinary tract. They are defined as hard deposits made of minerals and salts that accumulate in the kidneys. This condition arises due to concentrated urine, which facilitates the aggregation of minerals into crystal formations. While there is no single cause for kidney stones, several factors can increase their likelihood of development. Kidney stones typically occur when urine contains a high concentration of substances such as calcium, uric acid, or oxalates relative to the amount of fluid present. A lack of substances that prevent crystals from adhering can also create an environment conducive to stone formation. Identifying the type of kidney stone can help ascertain the underlying cause and mitigate the risk of future stones. Symptoms often include severe pain in the back, sides, and lower rib area, which may vary in intensity and location as the stones move through the urinary tract. Pain may also radiate to the lower abdomen and thighs, presenting in waves of varying severity alongside discomfort during urination.

Polycystic Kidney Disease

Polycystic kidney disease (PKD) is an inherited condition, either from one or both parents, characterized by the growth of numerous fluid-filled cysts within the kidneys, particularly in the nephron structure, which can cause the kidneys to become significantly enlarged, potentially weighing up to 30 pounds. This can lead to chronic kidney disease. PKD is classified into two main types:

Autosomal Dominant Polycystic Kidney Disease: The more common type of PKD, typically emerging due to a genetic defect resulting in kidney cyst formation. Symptoms generally present between the ages of 30 to 50, though some individuals may be born with the disease, accounting for about 10% of cases. Common symptoms include back or side pain, hematuria, and headaches.
Autosomal Recessive Polycystic Kidney Disease: This rarer type causes cysts to develop in both the kidneys and liver and requires both parents to carry the gene responsible for the disease. Notably, affected infants may show symptoms shortly after birth or even prenatally, including high blood pressure, abdominal swelling, respiratory issues, and abnormal growth patterns, in addition to vomiting. Severe cases may lead to kidney and liver complications such as urinary tract infections, high blood pressure, ongoing flank pain, and growth restrictions.

Kidney Trauma

Kidney trauma refers to injuries caused by external forces impacting the kidneys. Damage may affect the kidneys alone or involve other organs as well. Types of kidney trauma include:

Blunt Kidney Trauma: This type is caused by objects or forces that do not puncture the skin, such as falls, car accidents, or blunt force impacts to the flank area. Common indicators include hematuria, visible or microscopic blood in urine, with possible external signs like bruising on the back or abdomen.
Pentrating Trauma: Resulting from objects that create a puncture wound, such as knives or bullets, penetrating trauma can lead to visible injuries, although these may not always be in proximity to the kidneys.

Renal Vein Thrombosis

Renal vein thrombosis occurs when a blood clot forms in one or both of the major veins carrying blood away from the kidneys. This condition typically arises due to hypercoagulability associated with nephrotic syndrome, which manifests through symptoms such as elevated protein levels in urine, high cholesterol, decreased serum albumin, and edema in various parts of the body. Contributing factors to renal vein thrombosis include benign kidney tumors, diabetic nephropathy, pregnancy, amyloidosis, and lupus, among others. Symptoms may include nausea, hematuria, vomiting, reduced urine output, and flank pain, with acute cases presenting sudden, severe pain in the upper renal area, while chronic cases may lack overt symptoms.

Hydronephrosis

Hydronephrosis, or swelling of the kidney, results from incomplete drainage of urine via the urinary tract. Any structural abnormalities within the urinary system can disrupt normal urinary flow, causing a back-up of fluid in the kidneys. Common causes in adults include kidney stones, tumors, and urinary retention, while in infants, changes at birth may predispose to hydronephrosis. In adolescents, kidney stones are often the culprit. The resulting pain may appear suddenly or be severe, often localized to the back or side.

Kidney Cancer

Kidney cancer can also be a source of kidney pain. While the exact causes of kidney cancer remain uncertain, several risk factors are associated with its development, including hypertension, prolonged dialysis, genetic predispositions, family history, and obesity. Individuals with a body mass index (BMI) of 30 or greater face increased risk. Kidney cancer is relatively rare in those under fifty, typically affecting individuals in their sixties and seventies. Symptoms often include persistent pain in the lower back or side, particularly beneath the rib cage.

Causes of Severe Kidney Pain

Renal colic is characterized by intense dolor in the lower back or flanks, usually felt more significantly on one side. This pain tends to develop swiftly, with intermittent episodes that worsen over time. Severe kidney pain typically arises from a blockage in the urinary tract, which can originate in the kidneys, ureters, bladder, or urethra. The most common causes of urinary obstruction include kidney stones, blood clots, ureteral contractions, and necrotic tissue obstructing urine flow.

When to See a Doctor

Certain conditions warrant medical consultation for kidney pain; these include:

Persistent pain in one or both sides of the back.
Recent urinary tract infection.
Back or flank pain accompanied by other symptoms such as fever, changes in urine color, painful urination, hematuria, frequent urgency to urinate, or passage of solid material resembling stones in urine, alongside general fatigue.

Video on Causes of Kidney Pain

Although kidney pain can be troublesome, it serves as an important indicator of underlying issues that require treatment before they deteriorate. What are the common causes of kidney pain?

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Notes:

(*) Edema: Swelling caused by the accumulation of excess fluid in body tissues, particularly the skin.
(*) Amyloidosis: A rare group of diseases resulting from abnormal deposition of amyloid protein in various body tissues, produced in the bone marrow.
(*) Lupus: A long-term autoimmune disease where the immune system attacks healthy body tissues.