Case Author(s): Anton J. Johnson, M.D., Ph.D. and Tom R. Miller, M.D., Ph.D. , 7/26/96 . Rating: #D2, #Q3

Diagnosis: Metabolic bone disease secondary to renal failure.

Brief history:

17 year-old male with fatigue, weight loss, and fever.


Anterior and posterior images are shown.

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Full history/Diagnosis is available below

Diagnosis: Metabolic bone disease secondary to renal failure.

Full history:

17 year-old male patient with fatigue, weight loss, and fever. Laboratory results include elevated BUN, creatinine, and phosphate with decreased serum levels of calcium. The patient also has a history of chronic renal disease.


18.2 mCi Tc-99m MDP i.v.


Whole-body bone scintigraphy demonstrates diffusely increased skeletal uptake, minimal soft tissue and renal uptake and no bladder activity. There are no focal bony lesions.


The most important aspect of interpretation of a "superscan" on bone scintigraphy is to properly identify it as abnormal -- the lack of focal bony abnormalities tends to be misleading. Near total absence of renal and soft tissue activity, however, should prompt the interpreter to consider the presence of a superscan. The differential diagnosis for a true superscan is essentially limited to metabolic versus diffuse metastatic disease. The word "true" is included because a superscan appearance can be artificially obtained by a prolonged delay before imaging (e.g. 6 or more hours rather than the usual 2-3 hours after injection). The additional time allows for more renal and soft tissue clearance of tracer with resultant greater bone-to-soft tissue activity. Fortunately, this is an infrequent problem and one that can be identified by noting an abnormally long delay from time of injection to imaging.

Given a true superscan, clinical history is frequently all that is necessary to suggest the correct diagnosis. Prostate carcinoma is the most common of the metastatic causes, with breast and lymphoma as other less likely possibilities. Renal disease and hyperparathyroidism (primary or secondary) lead the list of metabolic causes of superscans. Typical histories would include an elderly male with a significantly elevated PSA (suggesting metastatic prostate carcinoma) or a patient with chronic renal failure and/or laboratory evidence of renal disease (suggesting a metabolic etiology). In this teaching file case, the patient's young age, history of chronic renal disease, and abnormal laboratory values clearly point to metabolic disease as the cause of his superscan. Without this clinical information, however, metastatic disease would remain in the differential, although widespread metastases typically show less involvement of the extremities and are usually not completely uniform and symmetric compared to metabolic bone disease.

References: Datz FL: Handbook of Nuclear Medicine, 2nd ed. St. Louis, Mosby, 1993, pp67-69. Datz FL, et al: Nuclear Medicine, A Teaching File, St. Louis, Mosby, 1992, p26. Mettler FA, Guiberteau MJ: Essentials of Nuclear Medicine, 3rd ed. Philadelphia, W.B. Saunders, 1991, p217. Thrall JH, Ziessman HA: Nuclear Medicine, the Requisites, St. Louis, Mosby, 1995, pp102,120.

Major teaching point(s):

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Differential Diagnosis List

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ACR Codes and Keywords:

References and General Discussion of Bone Scintigraphy (Anatomic field:Skeletal System, Category:Metabolic, endocrine, toxic)

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Case number: bs062

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