Kidney stones: Symptoms, causes & diagnosis

Kidney stones are hard deposits made of minerals and salts that form inside your kidneys. This common health problem can cause severe pain and urinary issues if not addressed. Understanding the symptoms, diagnosis, and treatment options for kidney stones is the first step toward prevention. This article explores the causes and management of this medical condition.

💡 In short:

  • Kidney stones are hard deposits formed by excess minerals like calcium and uric acid in concentrated urine, often resulting from dehydration or metabolic conditions like diabetes.
  • The primary symptom of a kidney stone is renal colic: severe, sharp pain in the side and back that often radiates to the abdomen, accompanied by changes in urinary frequency or blood in the urine.
  • Diagnosis involves imaging (like CT scans) and urine analysis, while treatment and long-term prevention focus on increasing water intake and specific diet or medicine adjustments based on the stone's composition.

Common symptoms of kidney stones

The symptoms of kidney stones often become apparent when a stone moves within the kidneys or enters the ureter, a critical part of the urinary tract (the tube connecting the kidneys to the bladder). This movement can cause severe pain known as renal colic. This common health issue affects approximately 1 in 11 people, leading to intense pain or complications if the blockage affects the flow of urine.

Key symptoms include:

Severe pain: Sharp, cramping pain typically in the side and back, below the ribs (flank pain). This pain can radiate to the lower abdomen and groin, often coming in waves and varying in intensity.

Urinary changes: Persistent need to urinate, urinating more often than usual, or passing small amounts of urine.

Painful urination: A burning feeling during urination (dysuria).

Hematuria: Pink, red, or brown urine due to blood (hematuria). Sometimes, only microscopic amounts of blood are present, visible only through testing.

Other associated symptoms: Nausea and vomiting are common. Fever and chills may indicate a serious infection and require immediate medical attention.

Important ⚠️ If you experience sudden, severe pain or pain accompanied by fever/chills or blood in your urine, contact a doctor or seek healthcare immediately.

What causes kidney stones?

Kidney stones form when your urine contains more crystal-forming substances—such as calcium oxalate, and uric acid—than the fluid in your urine can dilute. Persistently low water intake is a major contributor, leading to concentrated urine where this acid and these minerals can solidify.

The main types of kidney stones are:

Stone Type Primary Composition Associated Causes / Risk Factors
Calcium Stones Calcium oxalate (most common) or calcium phosphate High levels of calcium or oxalate in the urine, a high-salt diet, hyperparathyroidism, or certain genetic factors.
Uric Acid Stones Uric acid High-protein diet, gout, chronic diarrhea, or diabetes. Often associated with low urinary pH (more acidic urine) and high uric levels
Struvite Stones Magnesium ammonium phosphate Typically, the result of chronic urinary tract infections.
Cystine Stones Cystine (an amino acid) Caused by cystinuria, a hereditary genetic disease where the kidneys excrete excessive cystine.

Several factors increase the risk of developing kidney stones:

Dehydration

Not drinking enough water is a major cause.

Diet

A high-sodium, high-protein, or high-oxalate diet (in some cases) can increase the concentration of stone-forming substances in the urine.

Medical conditions

Conditions like obesity, inflammatory bowel diseases, gout, and type 2 diabetes significantly increase risk, particularly for uric acid stones.

Family history

Having a family member with kidney stones increases your own risk.

Diagnosis of kidney stones

A prompt and accurate diagnosis is crucial for guiding appropriate treatment and ruling out other serious diseases.

The diagnosis process typically involves:

Medical history and physical exam: The doctor will assess your symptoms and personal risk factors.

Blood and urine tests: Blood tests may reveal excessive amounts of calcium or uric acid in your bloodstream and check for proper kidney function.

Urine tests, including a 24-hour urine collection, help your doctor measure the volume of urine produced and the levels of stone-forming and stone-preventing substances. Monitoring urine is key to prevention. For those at high risk, new tools like Withings U-Scan, a toilet embedded urine lab, can help you and your doctor track your health by checking key biomarkers like calcium levels and hydration status directly from your toilet.

Imaging tests such as:

CT Scan: A computed tomography (CT) scan is often the preferred imaging method to visualize the size and location of the kidney stones in the urinary tract.

Ultrasound: Ultrasound is a non-invasive tool, especially useful during pregnancy or when avoiding radiation is necessary, though it can sometimes miss smaller stones.

Stone analysis: If you pass a stone, your doctor may ask you to collect it using a strainer. Analyzing the stone's chemical makeup helps determine its type (calcium, uric acid, etc.), which is essential for tailoring prevention and treatment strategies.

Prevention and treatment strategies

Medical treatment for active stones

Effective treatment for acute episodes focuses on managing pain (often with NSAIDs) and facilitating stone passage. For stones too large to pass or associated with infection, your doctor may recommend procedures like extracorporeal shock wave lithotripsy (ESWL) or surgery.

Long-term prevention and diet

For long-term prevention, the primary recommendation for all types of kidney stones is increasing water intake to dilute the urine. Other preventative measures are specific to the stone type:

Calcium Stones: Adjusting the diet to reduce sodium and animal protein, while ensuring adequate, not excessive, dietary calcium. Thiazide diuretics or citrate medicine may be prescribed by your doctor.

Uric Acid Stones: Limiting high-purine foods (like red meat) and maintaining a healthy body water balance. Medications like allopurinol can reduce uric acid levels in the blood and urine, and alkalinizing agents can make the urine less acidic.

Regular follow-up with your healthcare provider is essential, as the recurrence risk for kidney stones is high. Consistent monitoring of your health and urinary biomarkers is key to successful prevention. This is where tools like Withings U-Scan Calci can provide valuable insights. By placing the U-Scan Calci device in your toilet, you can proactively monitor crucial biomarkers for kidney stone formation, such as urine hydration and calcium levels, helping you and your doctor take timely action to avoid recurrence.

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