Kidney stones are solid formations of minerals and salts that develop within the kidneys. While they can remain unnoticed for a period, symptoms typically arise when a stone moves into the narrow tubes of the urinary tract. The duration of these symptoms, and the time it takes for a stone to pass, can vary significantly among individuals. Many kidney stones are small enough to pass out of the body naturally, though this process can be quite painful.
Factors Determining Stone Duration
Stone size primarily influences how long symptoms persist. Smaller stones, generally less than 4 millimeters, often pass within one to two weeks, with around 80% passing on their own. Larger stones, particularly those over 6 millimeters, may take much longer, potentially weeks or months, and are less likely to pass without medical intervention. Stones between 4 and 6 millimeters might take up to 45 days to pass naturally.
The stone’s location within the urinary tract also plays a role. Stones in the kidney may not cause pain until they move into the ureter, the tube connecting it to the bladder. Once in the ureter, the stone’s position along this pathway affects passage speed; stones closer to the bladder tend to pass more quickly. Stone composition, such as calcium oxalate, uric acid, or struvite, does not directly dictate passage time but can influence treatment approaches if intervention becomes necessary.
Individual urinary tract anatomy can impact how easily a stone moves. Some people may have narrower ureters or other structural differences that hinder passage. Adequate hydration also helps, as sufficient fluid intake increases urine flow, facilitating stone movement.
The Journey of a Kidney Stone
Symptoms of a kidney stone often begin abruptly with severe pain, known as renal colic, as the stone starts to move from the kidney into the ureter. This pain is typically felt in the side and back, below the ribs, and may spread to the lower abdomen and groin. The intensity of this pain can fluctuate, coming in waves as the body attempts to push the stone along.
Alongside the severe pain, other common symptoms can include nausea and vomiting. Individuals may also notice blood in their urine (pink, red, or brown), and experience a frequent or urgent need to urinate, sometimes with a burning sensation. Once a stone reaches the bladder, the intense pain often subsides, though there might be a feeling of pressure and a persistent urge to urinate.
The journey of a kidney stone can last from a few days to several weeks. While the pain can be significant during this journey, symptoms usually resolve completely once the stone has exited the body through urination.
When Medical Intervention is Needed
There are specific situations where a kidney stone is unlikely to pass on its own or poses a health risk, necessitating prompt medical attention. Unmanageable pain that cannot be controlled with prescribed or over-the-counter pain relievers is a clear indicator to seek help. Persistent and severe pain, especially if it worsens, warrants medical evaluation.
Signs of infection, such as fever, chills, or shaking, alongside kidney stone symptoms, require immediate medical care. An infection in the urinary tract, particularly when a stone is causing an obstruction, can become serious. A complete blockage of urine flow, indicated by an inability to urinate or significantly decreased urine output, is also an urgent concern.
Furthermore, persistent nausea and vomiting that lead to dehydration should prompt a visit to a healthcare provider. If symptoms continue for several weeks without the stone passing, or if imaging reveals a large stone, medical intervention may be necessary. Individuals with pre-existing conditions like a single kidney or kidney disease should also seek medical attention more quickly if they suspect a kidney stone.