Understanding kidney pain: Common causes, symptoms and when to get checked out

Kidney cancers don’t generally cause pain in patients before diagnosis. That’s because the most common types of kidney cancer tend to grow very slowly, so they gently push other organs aside as they get larger.

But what does kidney cancer pain feel like? And what causes the rest of the sensations people often describe as “kidney pain?” Read on to find out.

Kidney cancer pain is dull, achy and persistent

Only about 10% of patients with kidney cancer report experiencing flank or abdominal pain as a symptom of the disease. When they do, it’s usually described as a dull, persistent ache that worsens over time, rather than a sudden, sharp pain.

That’s because the kidney capsule — or outermost layer of tissue covering the organ — is the part that contains the most nerve endings. 

So, unless something like sudden bleeding within a tumor quickly stretches out the kidney capsule, there is no such thing as true kidney cancer pain. However, if a kidney tumor spreads to other organs such as the bone, it can sometimes cause bone pain.

Another reason patients might experience pain in the kidney area is when bleeding flows down a ureter and causes an obstruction there with clots. But I’ve seen patients with kidney tumors up to 25 cm (almost 10 inches) wide, and yet they report no pain. 

Reasons for other types of ‘kidney’ pain

Pain in the abdomen or flank, on the other hand, can be attributed to many different causes, including several non-cancerous conditions. These include:

• Kidney stones
• Musculoskeletal problems
• Pyelonephritis: a urinary tract infection in the kidney
• Hydronephrosis: when a ureter is blocked by a kidney stone or pinched shut in some other way, causing a backup of urine
• Polycystic kidney disease: a genetic condition that causes both kidneys to become filled with innumerable cysts
• Renal vein thrombosis: a rare type of clot that can obstruct the flow of blood from the kidney

But kidney cancer pain is a very different type of pain from the kind people typically experience with any of these other conditions. The severe, sudden pain of a kidney stone passing, for instance, stems from the ureter being stretched out as the stone makes its way down that tube to the bladder.

When to get ‘kidney pain’ checked out

Unfortunately, no screening test currently exists for kidney cancer. So, there’s no blood test, urine test, or imaging scan we can do to detect it early in the average person. That’s why you should have any persistent pain in your abdomen or flank checked out by a physician for a formal diagnosis. 

However, most bladder cancers are detected through blood in the urine. So, blood in the urine should absolutely not be ignored. And, anyone who experiences it should be evaluated by a urologist. Any blood in the urine should also be considered serious until proven otherwise.

José Karam, M.D., is a urologic surgeon specializing in kidney and other genitourinary cancers.

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