Conclusions: The CG and MDRD formulas had some limitations for proper GFR estimation and K/DOQI-CKD classification by GFR levels alone.

Cockcroft-Gault prediction could be used for children over 12 years of age and adults; it should not be considered as creatinine clearance but as GFR corrected for body surface, it is merely a prediction, 95% of the results are between +/-40 mL/min/1.73 m(2) in children and +/-30 mL/min/1.72 m(2) in adults. In younger children no formula is satisfying.

Postural instability can be the result of various factors, including fatigue. Although it is well known that exercise-induced fatigue may be responsible for a decrease in performance, its effects on postural control, as well as those of hydration, have been relatively little explored. This study evaluated the effects of fatigue, with and without rehydration, on postural control in 10 healthy subjects who regularly practice sports activities. All subjects were submitted to three types of ergocycle exercises: maximal oxygen uptake (Vo2max) and submaximal exercises in no-hydrated and hydrated conditions at a power corresponding to approximately 60% of the Vo2max of each subject. Static posturographic tests were performed immediately before (control) and after exercises. The postural control performance decreased from the best to the worst: control, hydration, dehydration, and Vo2max. Fast Fourier transformation of the center of foot pressure showed three patterns of amplitude spectral density, with an increase of spectral amplitude for dehydration, more important for Vo2max conditions. Spectral amplitudes for control and hydration conditions were relatively similar. This hierarchy suggests that fatigue mainly alters muscular effectors and sensory inputs, such as proprioception, resulting in poor postural regulation. Moreover, fluid ingestion could be responsible for the preservation of muscular functions and of sensory afferences accurately regulating postural control.

SummaryThe GFR has a paramount diagnostic and staging role in the Kidney Disease Outcome Quality Initiative Clinical Practice Guidelines for Chronic Kidney Disease (K/DOQI-CKD). The most widely used serum creatininebased formulas in adults for estimated GFR (eGFR) are the Cockcroft-Gault (CG) and Modification of Diet in Renal Disease Study (MDRD). Recently, a new Chronic Kidney Disease Epidemiology Collaboration equation has been developed. Review of the literature revealed that CG and MDRD formulas correctly assigned overall only 64% and 62%, respectively, of the subjects to their actual K/DOQI-CKD classification's GFR groups as determined by measured GFR (mGFR). This suggests that approximately 10 million (38%) subjects may have been misclassified on the basis of estimated CKD prevalence of 26.3 million adults in the United States. The purpose of this review is to help the clinician understand the limitations of using eGFR in daily practice. We also elaborate upon issues such as the differences among markers of mGFR, the validity of adjusting GFR for body surface area in certain populations, the limited data on boundaries for normal mGFR according to age, gender, and race, the need for calibration of a wide spectrum of serum creatinine measurements, the lack of actual eGFR value above 60 ml/min per 1.73 m 2 and reference for normal mGFR in the clinical laboratories' reports, and the performance evaluation of the eGFR formulas. Several pitfalls have to be overcome before we can reliably determine health and disease in daily nephrology practice to preserve the first rule of practicing medicine: primum non nocere.Clin J Am Soc Nephrol 6: 937-950, 2011.

Systemic lactate deprivation is detrimental to myocardial energetics, cardiovascular performance, and outcome.