ESPE Abstracts (2015) 84 P-3-657

ESPE2015 Poster Category 3 Bone (47 abstracts)

Discrepancy in Bone Age Rating Using Tanner-Whitehouse Rating and Automated Bone Age Determination in a Child Who was Later Diagnosed with Metaphyseal Dysplasia

Niels Birkebæk & Michel Hellfritzsch

Aarhus University Hospital, Aarhus, Denmark

Background: In the last 50 years bone age has been manually evaluated using the method of Tanner and Whitehouse. Recently automated image analysis has been introduced for bone age determination. The automated method shows good agreement with manual evaluation; further, the precision of the automated method may be higher compared to the manual method.

Objective and hypotheses: To report on the discrepancy of bone age determination using the manual TW2 method and the automated – boneXpert – TW3 method in a patient with metaphyseal chondrodysplasia.

Method: A 4.8 year old girl was admitted due to nanismus with a height of 92 cm (−3½ S.D.) and a weight of 15 kg (−1.5 S.D.). Her birth weight was 3.6 kg and birth length was 48 cm. Parents were ethnic Danish and 183 and 180 cm respectively. The girl suffered no chronic diseases, had normal thyroid function, a normal growth provocative test and a normal female karyotype. She had a manual and automated bone age determination at the ages of 5.9 and 8.5 years. Further, she had a whole body x-ray examination and genetic examination.

Results: At 5.9 years old the bone age was 6.7 years (manual) and 4.1 years (boneXpert) respectively, and the radiologist suspected bone disease. At 8.5 years old the bone age was 9.1 years (manual) and 5.4 years (boneXpert) respectively. Whole body x-ray examination was compatible with metaphyseal chondrodysplasia – McKusick type. Genetic examination confirmed the radiologic diagnosis with a homozygous pathogenic mutation-g.70A>G – in the RMRP gene.

Conclusion: Children with metaphyseal dysplasia may show significant discrepancies in bone age when rated with the manual TW2 method and the automated – boneXpert – TW3 method. This may hamper adult height prediction. The manual method has the opportunity of evaluating bone structure and come up with proposals for further examinations.

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