The Difference Between Kidney Pain and Lower Back Pain

Kidney pain and lower back pain involve a similar symptomology. However, they differ in terms of etiology, epidemiology, and treatment.

Written and verified by el biólogo Samuel Antonio Sánchez Amador.

Last update: 04 July, 2023

We’ve all felt lower back pain. In fact, lower back pain is the most common musculoskeletal disorder in the world, and (almost) all human beings go through an acute condition at least once in their life. In most cases, this condition isn’t serious, but it can be confused with others. Here, we’ll show you the difference between kidney pain and lower back pain.

Although it may seem anecdotal, knowing the distinctions between the two disease groups is essential, as one may represent a serious medical emergency and the other tends to be milder. If you want to know the etiology of these conditions and their underlying causes, we encourage you to continue reading.

Musculoskeletal disorders and kidney disease

We’ll begin by dissecting the differences between the two terms with the groups to which they belong. Lumbago is a type of musculoskeletal disorder, that is, it’s part of the conditions of ligaments, muscles, nerves, tendons, or structures that support the legs, arms, neck, and back.

These diseases usually find their cause in the performance of a sudden effort (or one that’s demanding and repeated over time). The World Health Organization (WHO) gives us some interesting data on the situation of musculoskeletal disorders globally:

• It’s estimated that 1.710 million people have musculoskeletal disorders worldwide.
• Lower back pain is the most common, and it affects a minimum of 568 million patients per year.
• This group of diseases represents the leading cause of disability worldwide. On its own, lower back pain is the main disabling condition in 160 countries.
• The prevalence of musculoskeletal disorders is increasing and the situation isn’t expected to be better in the future. The increase in cases is likely related to the general aging of the population.

Lower back pain is a leading clinical entity in the field of musculoskeletal disorders. Virtually all of us suffer from it acutely at some point in our lives, but as we’ll see below, it’s rarely explained.

On the other hand, kidney pain is a symptom that the kidney environment is suffering in some way, thus indicating kidney disease or nephropathy. This term includes all damage, disease, or abnormality that occurs in the kidneys.

The National Kidney Foundation provides us with a series of data of great interest that put the prevalence of kidney disease into perspective. You have them in the following list:

• Chronic kidney disease (one of the most serious kidney conditions) kills more people than prostate and breast cancer.
• This serious condition affects 37 million people in the United States, that is, 15% of the adult population (1 in 7 inhabitants).
• Approximately 90% of people with kidney disease don’t know they have them.
• 1 in 3 people in the US are at risk for kidney disease.
• Severe kidney disease is caused mainly by 2 conditions: 1 in 3 adults with diabetes and 1 in 5 with high blood pressure will suffer from them.

Kidney pain is a symptom of kidney disease, but it should be noted that not all kidney disease leads to chronic kidney disease (CKD). In any case, it’s crucial to monitor this clinical sign in case the damage to these organs is serious.

Differences between kidney pain and lower back pain

Now you know that lumbago (or lower back pain) is part of musculoskeletal disorders and that kidney pain is a symptom of nephropathy. Let’s take a closer look at the differences between the two terms.

1. Lower back pain can be a clinical entity, but kidney pain is a symptom

Lower back pain has its own term: Lumbago. As indicated by the National Library of Medicine of the United States, this condition is defined as pain that’s felt in the lumbar region (vertebrae L1 to L5), which can also be accompanied by stiffness in the back, decreased movement, and difficulty staying upright.

Although pain alone is always a symptom, lower back pain can be viewed as an isolated disorder from other conditions. Ninety percent of lower back pain is idiopathic or nonspecific, so an underlying cause for this discomfort is rarely found. Although it seems obvious, highlighting this point is essential.

On the other hand, kidney pain is always a symptom and not a disease by itself, as it’s not usually an isolated disorder. This discomfort is always derived from kidney stones, infections, inflammation, cysts, polycystic kidney disease, and other nephropathies.

2. Different causal agents

The main difference between kidney pain and lower back pain lies in the etiology. Although most lower back pain conditions are idiopathic, they’re divided according to their possible trigger into several categories. On the other hand, in kidney pain, there are more specific causes.

Causes of lumbago

Lower back pain is a very general clinical entity. As indicated by the Statpearls portal , this table can be divided into the following fronts:

1. Mechanical: In most cases, lower back pain is believed to result from damage to the lumbar vertebrae, intervertebral discs, or adjacent soft tissues (muscles and tendons). Tension in the quadratus lumbar or paraspinal muscles is always suspected. A herniated disc is a common type of traumatic back pain.
2. Degenerative: Spinal osteoarthritis causes low back pain. Over time, intervertebral discs wear out and friction can occur between vertebrae and adjacent structures. This process is associated with age.
3. Inflammatory: A perfect example of inflammatory low back pain is ankylosing spondylitis. It’s a type of arthritis, and therefore, it’s autoimmune in nature.
4. Oncological: Spinal cord tumors and lesions derived from metastasis can cause nerve compressions that cause a lot of pain. Although this is a very rare cause, it must be taken into account.
5. Infectious: The entry of bacteria into the spinal environment causes inflammation and, therefore, pain.

If we want an idea to stand above the rest, it’s undoubtedly the following: As indicated by professional sources, up to 90% of such pictures are idiopathic in nature. Therefore, talking about direct causality in lower back pain is very complex.

The causes of kidney pain

Kidney pain is a symptom more limited to a series of diseases. Some of them are the following:

• Kidney stones: Kidney stones are stones that are deposited in the urinary system during the process of urine formation and release. There are 4 main types of stones: Calcium, uric acid, struvite, and cystine. They cause sudden and very stabbing kidney pain.
• Kidney infection: Also known as pyelonephritis, in this case, the bacteria from an infection settle in the kidneys and sometimes cause pain. The picture can be derived from an infection in the bladder, for example.
• Hydronephrosis: This condition represents an accumulation of fluid in the kidney. In general, it occurs because of a blockage in the upper part of the urinary tract.
• Kidney cyst: As the Mayo Clinic indicates, kidney cysts are round pockets of fluid that form in or on the kidneys. They can be associated with serious conditions (such as polycystic kidney disease), but in most cases, they’re isolated, generate few complications, and are asymptomatic.
• Polycystic kidney disease: An inherited condition in which an inordinate number of cysts form in the kidneys over time. It can be dominant or recessive.
• Kidney cancer: Kidney cancer is among the most common in both men and women. In males, the probability of presentation is 1 in 46, while in women, it’s 1 in 80.
• Renal thrombosis: In this case, a vein is obstructed that evacuates blood from the renal environment.
• Mechanical damage: A direct hit to the kidney area can cause kidney damage, resulting in severe pain.

As you can see, the etiology of kidney pain is much broader than that of low back pain. In addition, most of the time, the first symptom indicates a more or less serious condition (which can be greatly aggravated without treatment), while lower back pain doesn’t usually involve major complications.

3. Various symptoms

Without a doubt, the difference between kidney pain and lower back pain that you’ve been looking for is in this section. We already know the definitions and causes of both clinical signs, but the most important thing immediately is to know how to distinguish them at the symptomatic level to know when to go to the doctor.

Although both pictures are symptoms on their own (pain in the kidneys and pain in the vertebral environment), these can be accompanied by other more or less serious signs. For example, lumbago is usually accompanied by the following signs:

• Dull pain in the lower back (between the L1 and L5 vertebrae).
• Difficulty of movement. This can be severe enough to prevent the patient from standing or moving.
• Localized sensitivity to palpation.
• Pain radiating down the groin, buttock, or upper thigh–a sign of a pinched nerve.
• Mild or severe muscle spasms.

On the other hand, kidney problems present with the following clinical signs:

• Pain in the kidneys
• Decrease in the volume of urine excreted (diuresis).
• Fluid retention. This causes swelling in the feet, knees, and ankles.
• Shortness of breath.
• Fatigue.
• Disorientation.
• Weakness and nausea
• A fever (in case of an infection).

As you can see, the symptoms that accompany each clinical entity are very different. Next, we’ll dissect a little more the location of the pain and other features, as it’s the most important thing when it comes to differentiating these conditions.

Pain location

Back pain usually affects the lower back, that is, the area between the beginning of the buttocks and the thoracic region (where the ribs end). On the other hand, kidney disease occurs on one or both sides and higher up, just below the rib cage.

In addition, kidney pain can feel more internalized, as it affects structures deeper than the vertebrae and the superficial muscles that cause (almost always) the lumbar picture. Making this distinction as a patient is tricky, but it can go a long way toward distinguishing between conditions.

Pain adjustment after postural changes

Lower back pain usually improves when the patient takes certain positions (such as lying down) and worsens when performing physical activities or demanding efforts. On the other hand, kidney discomfort is usually much more constant and doesn’t improve with postural changes. To treat this last condition, you have to find the underlying cause and solve it.

Stabbing or constant?

Low back pain caused by muscle damage is usually mild. However, if a nerve has been involved, the patient experiences a sharp burning that passes through the calf (although it rarely goes beyond the knee). If it lasts a few days or weeks, the lumbago is acute, but if it lasts for more than 3 months, it’s considered chronic.

On the other hand, a kidney condition can present with severe or mild pain. Many describe the presence of kidney stones as one of the most powerful and stabbing pains they’ve ever felt, while an infection in this area can present with a diffuse feeling of discomfort.

Accompanying symptoms

As you’ve seen in previous lists, kidney pain is usually accompanied by many symptoms related to the urinary system: Blood in the urine (hematuria), little or no urination, excess urination (polyuria), the feeling of not having emptied the bladder (urgency), and frequent, short-lived urination (frequency).

At the same time, lower back pain is usually accompanied by mechanical symptoms, such as difficulty in making certain movements, the need to change positions, and nerve radiation to the extremities. In the case of lumbago, the symptoms of the urinary system aren’t conceived.

What to do before in either case?

If you feel pain in your back, you’re probably suffering from acute low back pain. This shouldn’t be a concern, because as studies indicate, in its acute form, it occurs in 60-90% of the general population at some point. All of us have hurt (or will hurt) our lower backs for a few days.

On the other hand, it’s necessary to see a doctor if the pain persists for more than a few days, is disabling, or presents with urinary symptoms. You may have mistaken back pain for kidney damage, or your lower back pain may have a more serious cause. In any case, any discomfort that lasts for more than a week (or is accompanied by serious signs) requires medical attention.