OVERVIEW

What is the normal size of a kidney?

The kidney is part of the human urinary system, located on both sides of the lower back, shaped like a bean. Its length ranges from 9 to 12 cm, width is about 4–5 cm, and thickness is approximately 3–4 cm. The left kidney is slightly larger than the right, but the difference in adults does not exceed 2 cm.
The main functions of the kidneys are to excrete metabolic waste, toxins, and drugs from the body, regulate water and osmotic pressure, maintain electrolyte and acid-base balance, and perform endocrine functions.

What is renal atrophy?

Renal atrophy is an acquired condition caused by various factors leading to the loss of nephrons or insufficient blood supply to the kidneys, resulting in a reduction in kidney size and a decline or loss of physiological function. It is a pathological phenomenon observed in many kidney diseases.
Renal atrophy can occur unilaterally or bilaterally, with unilateral cases being relatively more common. It is not clinically specific and is often detected through imaging examinations.

Is renal atrophy contagious?

Renal atrophy itself is not contagious;
however, if it is caused by infectious diseases such as tuberculosis, there may be a risk of transmission.

Is renal atrophy hereditary?

Renal atrophy is an acquired condition and is mostly not considered a genetic disease. However, a small portion of renal atrophy related to genes or genetic combinations may involve hereditary factors.

Is renal atrophy reversible? Can the kidneys return to normal size afterward?

If renal atrophy is caused by arterial stenosis, timely improvement of blood supply to the kidneys may partially reverse the atrophy. However, tissues with completely lost function cannot be restored.

SYMPTOMS

What are the manifestations of renal atrophy?

Depending on the underlying cause of renal atrophy and the stage of the disease, different clinical symptoms may occur:

• Possible symptoms include nausea, vomiting, fatigue, edema, hypertension, anemia, and possibly proteinuria.

• Severe cases may present with uremic manifestations such as pericarditis, peripheral neuropathy, and central nervous system abnormalities (clinical symptoms may range from difficulty concentrating and drowsiness to seizures, coma, and death).

Why does renal atrophy cause anemia?

Erythropoietin in the human body is primarily produced by the kidneys. When renal atrophy occurs, functional renal parenchyma decreases, leading to reduced erythropoietin production and shortened red blood cell lifespan, resulting in anemia.

Why does renal atrophy cause hypertension?

In renal atrophy, the loss of renal parenchymal function weakens or eliminates the kidney's ability to excrete water and sodium, leading to water and sodium retention, increased blood volume, and elevated cardiac output.
Renal medullary interstitial cells also secrete various hypotensive substances, such as prostaglandin E2. As renal atrophy progresses, the production of these substances decreases.
If renal artery stenosis or obstruction is also present, it can activate the RAS system, causing abnormal secretion of renin-angiotensin, vasoconstriction, and increased peripheral resistance. These factors collectively contribute to elevated blood pressure.

CAUSES

What causes kidney atrophy?

The main causes of unilateral kidney atrophy include:

• Congenital renal hypoplasia;

• Unilateral renal artery stenosis;

• Post-obstructive kidney atrophy;

• Post-traumatic kidney atrophy;

• Chronic atrophic pyelonephritis;

• Autonephrectomy due to renal tuberculosis (complete calcification of the kidney with total loss of function);

• Late-stage renal vein thrombosis;

• Urinary tract malformations.

The main causes of bilateral kidney atrophy include:

• Chronic renal insufficiency;

• Chronic pyelonephritis;

• NPHP7 gene mutation.

DIAGNOSIS

What tests are needed for kidney atrophy?

• Renal color Doppler ultrasound and renal function tests are relatively basic and simple examination methods, which can assess kidney size, function, as well as interstitial and parenchymal lesions;

• Radionuclide renal scan: Helps evaluate split renal function;

TREATMENT

What are the treatment methods for kidney atrophy?

• For kidney atrophy, the primary focus should be treating the underlying disease, as it often represents the advanced stage of kidney disease. Active treatment for renal failure and uremia is necessary. If dialysis is required, it should be promptly initiated.

• If kidney atrophy is caused by vascular stenosis, improving blood supply can effectively alleviate the condition.

• For unilateral kidney atrophy with severe loss of function, surgical removal may be considered. In end-stage cases, a kidney transplant may be required.

What are the serious consequences if kidney atrophy is left untreated?

Kidney atrophy can lead to renal insufficiency, uremia, and severe complications such as hyperkalemia, acidosis, infections, and gastrointestinal bleeding, which may require emergency dialysis. While completely non-functional kidney tissue cannot be restored, reversible damage may improve to some extent with timely detection and intervention.

Can kidney atrophy be cured?

Kidney atrophy is a pathological process involving progressive fibrosis and loss of function in renal parenchyma and interstitial cells during kidney disease progression. Treatment mainly aims to prevent further atrophy of reversible kidney tissue, promote repair and regeneration of damaged cells, and delay the loss of kidney function.

How long can one live with kidney atrophy?

Even with complete loss of function in both kidneys, patients can still achieve a good survival rate through timely dialysis and kidney transplantation. However, if left unmanaged, complications like uremia can become life-threatening at any time.

DIET & LIFESTYLE

What should be paid attention to in daily life with kidney atrophy?

• Quit smoking and alcohol, maintain weight within the ideal range;

• Actively manage blood pressure and blood sugar;

• Avoid exposure to toxic substances and refrain from taking medications that may impair kidney function;

• Limit intake of protein, water, and salt to reduce the metabolic burden on the kidneys;

• Reduce consumption of high-potassium foods such as bananas and oranges.

PREVENTION

How to prevent kidney atrophy?

Actively treating primary kidney diseases can effectively prevent kidney atrophy.
For patients with kidney diseases, regularly measuring kidney size can help monitor disease progression. Early detection of abnormal kidney size plays a crucial role in timely treatment and achieving better therapeutic outcomes.