Increased Renal Uptake

Bilateral increased uptake (defined as kidneys showing diffusely increased radionuclide uptake greater than that of the lumbar spine in the posterior projection) is rare; it is present only in about 1% or less of bone scintigrams. The etiology of increased renal uptake are probably similar to the causes of increased uptake in other soft tissues, e.g. myocardium and muscle. These include excess tissue calcium which may occur subsequent to local tissue damage or necrosis, or when calcium phosphate level is elevated . Tissue damage is implicated in cases of acute tubular necrosis and following administration of chemotherapy, aminoglycosides, or amphotericin B; however, renal function impairment is not always present. Calcium phosphate product is elevated in hyperparathyroidism and hypercalcemia. Another proposed mechanism for increased renal uptake is iron overload. Iron can alter the biodistribution of bone agents, converting them into renal agents similar to technetium-iron-ascorbate . This mechanism is probably implicated in sickle cell anemia, and thalassemia major, although renal damage is often associated with sickle cell anemia.

• Acute Pyelonephritis
• Acute tubular necrosis (ref)
• Antibiotics (ref)
• Chemotherapy (ref)
• Hepatorenal syndrome
• Hypercalcemia (ref)
• Hyperparathyroidism (ref)
• Hypervitaminosis A
• Idiopathic
• Iron overload
• Medullary sponge kidney (ref)
• Multiple myeloma
• Nephrocalcinosis
• Radiation (ref)
• Radiographic contrast
• Renal artery stenosis
• Renal vein thrombosis (ref)
• Rhabdomyolysis (ref)
• Sickle cell anemia (ref)
• Thalassemia major
• Urinary tract obstruction (ref)

Chemotherapy

Posterior projection of bone scintigraphy demonstrates intense homogeneous uptake in both kidneys after chemotherapy.

Hypercalcemia

Whole-body bone scintigram shows significantly increased bilateral renal radiotracer accumulation as compared to the lumbar spine, in a patient with elevated serum calcium.

Sickle Cell Disease

Bone scintigram (posterior view) obtained in a patient shows with bilaterally nephromegaly with increased Tc-99m technetium methylene diphosphonate uptake.

Sickle cell disease.

The bone scintigram shows enlarged kidneys with intense radionuclide activity probably due to microinfarcts and iron deposition.

Primary hyperparathyroidism.

The bone scintigram shows diffuse intense radiotracer uptake in both kidneys secondary to nephrocalcinosis.