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Published on: December 5, 2016
Free Fatty Acids as an Indicator of the Nonfasted State in Children
Shavonne M Collins1,2, Miranda M Broadney1,3, Nejla Ghane1
1Section on Growth and Obesity, Program in Endocrinology, Metabolism and Genetics, Division of Intramural Research and.
Insights
Serum free fatty acid (FFA) levels can help determine if children are truly fasting for blood tests. A cutoff of <287 mEq/mL for FFA is highly accurate in identifying non-fasting children, aiding in accurate glucose homeostasis diagnosis.
Area of Science:
- Pediatric Endocrinology
- Metabolic Disorders
- Clinical Diagnostics
Background:
- Accurate glucose homeostasis diagnosis in children relies on fasting blood samples.
- Serum free fatty acid (FFA) concentrations are explored as a potential marker to distinguish fed versus fasted states in pediatric patients.
Purpose of the Study:
- To evaluate the utility of serum FFA concentrations in differentiating fed and fasted states in children.
- To establish a reliable cutoff value for FFA to identify non-fasting pediatric patients.
Main Methods:
- Receiver operating characteristic (ROC) curve analysis was used on glucose, insulin, and FFA levels from 442 inpatient (fasting) and 323 outpatient (post-glucose load) samples.
- Children aged 5-18 years with healthy weight, overweight, or obesity were included.
- Cross-sectional comparison of mean FFA and percentage of FFA values below the identified cutoff between inpatient and outpatient settings.
Main Results:
- FFA demonstrated significantly superior performance (P < .001) over glucose or insulin in identifying non-fasting status.
- An FFA cutoff of <287 mEq/mL achieved 99.0% sensitivity and 98.0% specificity for non-fasting.
- Outpatient FFA levels were significantly lower than inpatient levels (P < .001), with only 1.6% of inpatients and 9.7% of outpatients showing non-fasting FFA values.
Conclusions:
- Clinicians should not assume pediatric patients are adequately fasted for blood tests.
- Children appear less likely to be fasting at outpatient appointments, indicated by lower and more frequently suppressed FFA levels.
- An FFA value <287 mEq/mL serves as a sensitive and specific clinical cutoff for identifying non-fasting in children.
Background:
Ensuring children are fasting for blood draws is necessary to diagnose abnormalities in glucose homeostasis. We sought to determine if serum free fatty acid (FFA) concentrations might be a useful marker to differentiate the fed and fasted states among children.
Methods:
A total of 442 inpatient (fasting) and 323 (postglucose load) oral glucose tolerance test samples of glucose, insulin, and FFA from children (age 5-18 years) who had healthy weight, overweight, or obesity were examined by receiver operating characteristic (ROC) curve analysis to identify a cut point for nonfasting. In a cross-sectional study, we compared mean FFA and percentage of FFA values below this cut point as a function of inpatient (n = 442) versus outpatient (n = 442) setting.
Results:
The area under the curve of FFA was significantly better (P values < .001) than the area under the curve of glucose or insulin for identifying nonfasting. FFA <287 mEq/mL had 99.0% sensitivity and 98.0% specificity for nonfasting. Mean FFA was lower in outpatients than inpatients (P < .001); only 1.6% inpatient but 9.7% outpatient FFA values were consistent with nonfasting (P < .001).
Conclusions:
Clinicians cannot assume that pediatric patients are adequately fasted on arrival for fasting blood work. On the basis of having significantly lower outpatient than inpatient FFA values and more frequently suppressed FFA, children appeared less likely to be fasting at outpatient appointments. FFA value <287 mEq/mL was a sensitive and specific cutoff for nonfasting in children that may prove clinically useful.
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