We agree that reference values of serum uric acid can vary, based on age
and gender. Women tend to have lower levels (by 0.5 to 1.0 mg/dL) than
men, probably because of the uricosuric effect of estrogens [1].
However, in this study, we used the levels which are considered to
correlate with primary hypertension in nearly 90% of teenagers [2].
Moreover, the relation between uric acid and cardiovascular disease has
been observed not only with frank hyperuricemia (>6 mg/dL in women and
>7 mg/dL in men), but also with uric acid levels considered to be in the
normal to high range (>5.2 to 5.5 mg/dL) [3]. Therefore, we decided to
take this cut-off point in both genders. However, we agree that our
study dealt with hematological parameters and platelet count in
adolescents with ‘high normal’ uric acid levels rather than age- and
gender-based reference values [4,5].
With regard to the exclusion criteria, we would like
to clarify that primary hypertension was not an exclusion criteria.
Moreover, most of the children included in the study were referred to
our department in the primary care office because of elevated casual
blood pressure. Only children with secondary forms of hypertension were
excluded. Similarly, excluded children were diagnosed with diabetes, but
not with metabolic syndrome. We used the age- and gender-specific
adolescent metabolic syndrome criteria linked to the National
Cholesterol Education Program Adult Treatment Panel III.
References
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Contoyiannis P, Vassilopoulos P. The relationship of sex steroids to
uric acid levels in plasma and urine. Acta Endocrinol (Copenh).
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2. Feig DI, Johnson RJ. Hyperuricemia in childhood
primary hypertension. Hypertension. 2003;42:247-52.
3. Feig DI, Kang DH, Johnson RJ. Uric acid and
cardiovascular risk. N Engl J Med. 2008;359:1811-21
4. Southcott EK, Kerrigan JL, Potter JM, Telford RD,
Waring P, Reynolds GJ, et al. Establishment of pediatric
reference intervals on a large cohort of healthy children. Clin Chim
Acta. 2010;411:1421-27.
5. Kubota M, Nagai A, Tang L, Tokuda M. Investigation
on hyperuricemia in children with obesity or various pediatric
disorders. Nucleosides Nucleotides Nucleic Acids. 2011;30:1051-9.
6. Jolliffe CJ, Janssen I. Development of age-specific adolescent
metabolic syndrome criteria that are linked to the Adult Treatment Panel
III and International Diabetes Federation criteria. J Am Coll Cardiol.
2007;49:891-8.