Introduction
Enlargement of one or both kidneys is a diagnostic description given by the doctor after an imaging procedure such as ultrasound or computed tomography. The kidneys weigh approximately 120-180g. The normal length of a kidney is 9-13 cm, width 6 cm and thickness 3 cm.
Anatomically and physiologically, the right kidney is usually smaller and lighter than the left. Enlargements can occur in the kidney in the so-called renal pelvic calyx system, but also outside this calyx system in the renal cortex. Since the kidney is embedded in a solid connective tissue capsule, its acute expansion is limited and often associated with severe pain. Chronic diseases can lead to enlargement in the long term without pain.
Causes of kidney enlargement
The causes of an enlarged kidney are manifold. If, for example, there is a stone disease, the urine can accumulate in the renal pelvic calices system. This expands and is impressive, for example, when enlarged by sonography (ultrasound).
The accumulation of urine can also be caused by factors outside the kidney. If, for example, a tumorous event presses on the urinary tract, it can be displaced and lead to urinary congestion and thus to an enlargement of the kidney. Acute inflammation of the renal pelvis can lead to swelling due to water retention.
Increased urine production due to a deficiency of ADH (antidiuretic hormone) disturbs the kidney’s ability to concentrate the urine. This leads to urine excretion of several liters per day (diabetes insipidus) and is accompanied by enlargement of the kidneys. In addition, kidney cysts or kidney cancer can cause an increase in the size of the kidney. In diabetes mellitus, calcifications can also cause an increase in the size of the kidneys. Hereditary cystic diseases of the kidneys can also lead to greatly enlarged kidneys.
Diagnosis of kidney enlargement
The diagnosis of a kidney enlargement is often made by ultrasound. Here the position and size are determined. In addition, it is possible to see the flow of urine and any urinary stones.
Furthermore, possible masses inside or outside the kidney can be detected. In X-rays, kidney stones or urinary stones can be shown as the cause of the enlarged kidney. Computer tomography can also provide information about the cause.
With a vascular imaging by MRI of the kidney (magnetic resonance imaging), possible vascularization of a tumor or thrombosis of the renal artery can be seen. Laboratory tests of the blood and urine can also provide information about the cause. To clarify unclear inflammations, a tissue sample of the kidney can also be taken (kidney biopsy).
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