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Abnormal vs. Normal Kidney Size: Signs, Risks, Complications

Abnormal vs. Normal Kidney Size: Signs, Risks, Complications

Like all other organs in the human body, the kidneys must be checked at all times in order to determine if there are any causes for concern. So naturally, many of us wonder what a normal kidney size is and what it means for our health.

What is the Normal Kidney Size?

The normal kidney size is around 10 to 12 cm which is roughly smaller than a clenched fist. To be more specific, refer to the bullet points below for the normal kidney size based on age group:

  • Adult kidney size: 10-14 cm long for males and 9-13 cm long for females. The width ranges from 3-5 cm, 3 in antero-posterior thickness, and has a weight of 150-260 g. Usually, the left kidney is larger in size compared to the right kidney.
  • Child kidney size: It depends on their age and size.
    • 0 to 12 months: 5 cm
    • 2 months to 6 months: 5.7 cm
    • 6 months to 1 year: 6.2 cm
    • 1 year to 5 years: 7.3 cm
    • 5 years to 10 years: 8.5 cm
    • 10 years to 15 years: 10 cm
    • 15 years old and above: the kidney size for this particular age group is similar to the normal kidney size of adults.

normal kidney size

Why Would a Kidney Shrink?

A shrinkage of a kidney is called kidney atrophy. Kidney atrophy happens for two main reasons:

  • Congenital problem: the kidney does not fully develop since birth.
  • Another reason as to why kidneys shrink happens after birth and it can affect either one kidney or both kidneys. This happens when there is a low blood supply being sent to the kidney and/or the loss of nephrons.

Kidney atrophy also happens due to blockage and chronic infections. This shrinkage can lead to health issues such as kidney disease and the more it decreases in size the more severe the effects would be to the kidney. If both kidneys happen to shrink then that will lead to kidney failure.

Furthermore, small kidneys typically indicate an irreversible damage from a disease. In the Philippines, kidney shrinkage is commonly secondary to hypertension and diabetes, and long-standing kidney disease.

Why Would Kidneys Increase in Size?

A kidney that swells up is called hydronephrosis. This happens when there is a build-up of urine in the kidney. The urine is not drained out from the kidney due to blockage and this can happen to both kidneys.

Hydronephrosis happens for various reasons such as:

  • Congenital blockage
  • Blood clots
  • Pregnancy
  • Kidney stones
  • Scarring of tissue from surgeries or injuries
  • Non-cancerous enlarged prostate
  • Tumor or cancer
  • Urinary tract infection

Large kidneys are likewise commonly seen in disease such as diabetes, multiple myeloma and polycystic kidney disease.

How do you know if kidney size is abnormal?

In order to know if your kidney size is normal or not, you must go and see a doctor and have your kidneys checked via ultrasound or x-ray. The doctor will then measure whether or not it is abnormal or not.

After the doctor determines that your kidneys indeed decreased or increased in size, they might then perform further tests to check what caused this and proceed on suggesting appropriate intervention.


If a person gets diagnosed with kidney disease or kidney failure, they can develop complications such as:

  • Anemia
  • Bone disease
  • High potassium
  • Heart disease
  • Gout
  • Fluid buildup
  • Metabolic acidosis
  • High calcium
  • Anemia
  • Fluid buildup
  • Heart disease
  • Bone disease and high phosphorus
  • High potassium

Key Takeaways

It is important to know that the normal size of kidneys ranges from 10 to 12 cm; anything smaller or larger than that is a cause for concern. Have your kidneys checked in order to prevent severe issues from damaging them in the future.

Hello Health Group does not provide medical advice, diagnosis or treatment.

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Written by Jen Mallari Updated Jul 05, 2021
Fact Checked by Hello Doctor Medical Panel