Kidney stones are small, hard deposits formed when minerals and salts crystallize in the urine. They vary in size, from a grain of sand to, rarely, larger than a golf ball. While small stones may pass unnoticed, larger ones or those that obstruct the urinary tract cause uncomfortable and painful sensations.
The Evolving Sensation of a Kidney Stone
The pain of a kidney stone, known as renal colic, is typically abrupt and severe. This intense discomfort often begins in the flank (the area between the lower ribs and hip) or lower back. It is described as sharp, cramping, or wave-like, fluctuating in intensity. These waves, lasting 20 to 60 minutes, are caused by the ureter (the tube connecting the kidney to the bladder) attempting to push the stone through muscular contractions.
As the stone descends, the pain’s location shifts. From the flank or back, discomfort may radiate to the lower abdomen and groin. For men, this pain can extend to the penis or testicle.
Renal colic can be so intense that individuals find it difficult to remain still, often pacing or writhing to find comfort. This restlessness is characteristic of kidney stone pain, unlike other abdominal discomforts where stillness might bring relief. The pain can be constant, punctuated by acute, colicky episodes as the ureter spasms around the stone.
Pain intensity relates more to the degree of obstruction and the body’s reaction than solely the stone’s size. Even small stones cause significant discomfort if they impede urine flow, leading to pressure buildup or irritation. This pressure, inflammation, and muscle spasms contribute to the severe sensation.
Other Physical Sensations
Beyond the primary pain, a passing kidney stone often triggers other symptoms due to urinary tract irritation. Nausea and vomiting are common, stemming from shared nerve connections between the kidneys and gastrointestinal tract. Intense pain can also induce these symptoms.
Blood in the urine (hematuria) is another frequent symptom. This occurs as the stone scrapes against the delicate lining of the ureter and other urinary tract parts during passage. Urine may appear pink, red, or brown, indicating visible blood, or it may be microscopic and only detectable by a urine test.
As the stone nears the bladder and urethra, a burning sensation during urination (dysuria) may occur. This discomfort can resemble a urinary tract infection, and a kidney stone can sometimes lead to infection. An increased urge or frequent urination, often in small amounts, is also common as the stone irritates the bladder.
Urine might also appear cloudy or have a foul odor. These changes can indicate bacteria, if an infection has developed, or other substances. Occasionally, individuals may feel they cannot fully empty their bladder or experience difficulty urinating due to the stone’s position.
When to Seek Medical Attention
Many kidney stones, especially smaller ones, may pass spontaneously with supportive care like increased fluid intake and pain management. However, certain symptoms warrant immediate medical attention. A high fever (typically above 100.4°F / 38°C) accompanied by chills is a significant warning sign, indicating a serious kidney or urinary tract infection.
Inability to pass urine or a complete blockage of urine flow requires prompt medical evaluation, as this can lead to urine backing up into the kidneys and potential damage. Uncontrollable pain not relieved by over-the-counter medication, or persistent nausea and vomiting preventing adequate hydration, also signal a need for professional medical care.
Individuals with a single kidney or underlying conditions like diabetes or chronic kidney disease should seek medical help more readily if they suspect a kidney stone, as these conditions increase the risk of complications. While awaiting medical advice, maintaining hydration by drinking water can be helpful, but it should not delay seeking professional care for severe or concerning symptoms.