Neonatal urinary uric acid/creatinine [correction of ceratinine] ratio as an additional marker of perinatal asphyxia

The Urinary Uric Acid / Cr ratio as a marker of morbidity and mortality of preterm infants: a case-control study

BACKGROUND

Perinatal asphyxia is one of the main causes of preterm infant mortality. Some studies have shown that The Urinary Uric Acid / Cr (UUA/Cr) ratio may be used as an additional marker for perinatal asphyxia.This study intend to investigate the relationship of this ratio with outcomes of preterm infants admitted to NICU.

METHODS

This case-control study was carried on 102 preterm newborn infants with gestational age of 30 weeks to 33 weeks and 6 days admitted in the neonatal intensive care unit.The case group, consisted of 51 premature neonates with a history of intubation, cardiopulmonary resuscitation, mechanical ventilation and Nasal continuous positive airway pressure (NCPAP) at birth, were compared with 51 matched neonates. The UUA/Cr ratio was measured in the first 24 h after birth. Complications during hospitalization, duration of hospitalization, and final outcome were evaluated.

RESULTS

The mean level of UUA/Cr ratio in case and control group were 5.4 ± 4.1 and 3.6 9 ± 2.9 respectively and this difference was statistically significant (p = 0.014). The UUA/Cr ratio were significantly higher in females, cesarean section delivery, Apgar score ≥ 8, neonates without any complication and neonates with less than 10 days of hospitalization. However, this ratio has no predictive value for the incidence of complications during hospitalization and long-term hospital stay for infants of the case group.

CONCLUSIONS

The Urinary Uric Acid / Cr ratio in the first 24 h after birth in preterm neonates who underwent intubation, NCPAP or cardiopulmonary resuscitation was higher than healthy neonates.

Association of Uric Acid in Serum and Urine with Arterial Stiffness: Hanzhong Adolescent Hypertension Study

Background

Hyperuricemia has long been associated with increased cardiovascular risk, and arterial stiffness is proposed as a mediator. The present study is aimed at examining the associations of uric acid (UA) in blood and urine with arterial stiffness in a Chinese cohort.

Methods

A total of 2296 participants (mean age: 43.0 years) from our previously established cohort of Hanzhong Adolescent Hypertension Study were included. The participants were classified as subjects with or without arterial stiffness, which was defined as brachial-ankle pulse wave velocity (baPWV) ≥ 1400 cm/s and/or carotid intima-media thickness (CIMT) ≥ 0.9 mm. Multivariate regression analyses were used to examine the relationship between serum and urinary UA and the risk of arterial stiffness after adjusting for age, gender, systolic blood pressure, fasting glucose, BMI, heart rate, total cholesterol, and triglycerides.

Results

baPWV was positively correlated with urinary uric acid/creatinine ratio (uUA/Cre) (β = 0.061, P < 0.001), while CIMT was correlated with uUA/Cre (β = 0.085, P < 0.001) and fractional excretion of uric acid (FEUA) (β = 0.044, P = 0.033) in all subjects. In addition, uUA/Cre was significantly associated with the risk of high baPWV [1.032 (1.019-1.045)] and arterial stiffness [1.028 (1.016-1.040)].

Conclusion

Our study showed that urinary UA excretion was significantly associated with the risk of arterial stiffness in Chinese adults. These findings suggest that UA, especially urinary UA, may be used as a simple, noninvasive marker for early detection of arterial stiffness in otherwise healthy subjects.

Small molecule biomarkers for neonatal hypoxic ischemic encephalopathy

Hypoxic Ischemic Encephalopathy (HIE) is one of the most deleterious conditions in the perinatal period and the access to small molecule biomarkers aiding accurate diagnosis and disease staging, progress monitoring, and early outcome prognosis could provide relevant advances towards the development of personalized therapies. The emergence of metabolomics, the "omics" technology enabling the holistic study of small molecules, for biomarker discovery employing different analytical platforms, animal models and study populations has drastically increased the number and diversity of small molecules proposed as candidate biomarkers. However, the use of very few compounds has been implemented in clinical guidelines and authorized medical devices. In this work we review different approaches employed for discovering HIE-related small molecule biomarkers. Their role in associated biochemical disease mechanisms as well as the way towards their translation into the clinical practice are discussed.

Random urine uric acid to creatinine and prediction of perinatal asphyxia: a meta-analysis

Objective: The purpose of the present review is to evaluate whether urine uric acid to creatinine ratio is increased in perinatal asphyxia and hypoxic-ischemic encephalopathy (HIE), as well as to assess its predictive accuracy in the disease. Methods: We used the Medline (1966-2017), Scopus (2004-2017), Clinicaltrials.gov (2008-2017), Embase (1980-2017), Cochrane Central Register of Controlled Trials CENTRAL (1999-2017), and Google Scholar (2004-2017) databases in our primary search along with the reference lists of electronically retrieved full-text papers. The hierarchical summary receiver operating characteristic (HSROC) model was used for the meta-analysis of diagnostic accuracy. Results: Fourteen studies were finally included in the present review, that investigated 1226 neonates. Urinary uric acid to creatinine ratio was significantly higher in neonates with perinatal asphyxia than in healthy controls (mean differences (MD): 1.43 95%CI [1.17, 1.69]). Specifically, the mean difference for Sarnat stage 1 was 0.70 (95%CI [0.28, 1.13]), for stage 2 1.41 (95%CI [0.99, 1.84]), and for stage 3 2.71 (95%CI [2.08, 3.35]). The estimated sensitivity for the summary point was 0.90 (95%CI (0.82-0.95)), the specificity was 0.88 (95%CI (0.73-0.95)) and the diagnostic odds ratio was calculated at 63.62 (95%CI (17.08-236.96)). Conclusions: Urinary uric acid to creatinine ratio is a rapid and an easily detected biomarker that may help physicians identify neonates at risk of developing perinatal asphyxia and HIE. However, large-scale prospective studies are still needed to determine its value in predicting mortality, as well as short- and long-term adverse neurological outcomes.

Urinary Uric Acid/Creatinine Ratio - A Marker For Perinatal Asphyxia

BACKGROUND

Perinatal hypoxia is one of the leading causes of perinatal mortality in developing countries. Both apgar score and arterial blood pH predict the neonatal mortality in asphyxia. Apgar score alone does not predict neurologic outcome and as it is influenced by various factors. This study was conducted to evaluate the utility and sensitivity of urinary uric acid to creatinine ratio (UA/Cr ratio) in asphyxia diagnosis, compared to invasive Arterial Blood Gas (ABG) analysis.

AIM

To assess the urinary uric acid/creatinine ratio as an additional marker for perinatal asphyxia compared with ABG analysis in apgar score monitoring.

MATERIALS AND METHODS

The present case control study was conducted at a teaching hospital in Central Gujarat. Data of 40 healthy newborns and 40 asphyxiated newborns were collected. In absence of regional estimates, a sample of size 39 was required to attain a power of 80% at 5% alpha (type I error) considering a moderate effect size of 0.65. (UA/Cr) ratio was measured from the spot urine sample collected during 24-72 hours of birth. Statistical analysis was performed by Independent t-test, Pearson's correlation coefficient (r) and Receiver Operating Characteristic (ROC) plots.

RESULTS

The mean (UA/Cr ratio) (2.75±0.18 vs 1.78±0.23) is significantly higher in asphyxiated group than in the control group (p<0.0001). Urinary UA/Cr ratio had negative correlation with blood pH (r= -0.27, p=0.18), which was not significant (p>0.05). Urinary UA/Cr ratio with criterion of >2.3 had 100% sensitivity, 100% specificity with AUC of 1 (p<0.0001) had a better predictive value.

CONCLUSIONS

Apgar score is usually reduced in neonates with congenital anomalies and premature neonates. Hence, it is preferable that the clinical diagnosis of asphyxia by apgar scores be supported by other investigations so that early decision can be taken about the level of care the baby needs. pH, lactates and base deficits change with establishment of respiration following resuscitation. However, pH, lactate, base deficit estimations are invasive and need rapid estimations. Non-invasive urinary UA/Cr ratio may be an answer to these issues as it easy, economical and equally efficient.

Uric acid and the kidney

Uric acid, the end product of purine metabolism, is excreted predominantly by the proximal tubules. Abnormal serum levels of uric acid are due to alterations in production or excretion. Fractional excretion of uric acid is helpful in determining the underlying etiology of hypouricemia or hyperuricemia in children. Abnormalities in the molecular mechanisms that control renal uric acid tubular transport are implicated in various disorders associated with abnormal uric acid levels. Gout is rare in children; yet its presence necessitates evaluation for enzymatic defects in purine metabolism. Well-known effects of uric acid on the kidney include nephrolithiasis and acute kidney injury (AKI) in the setting of tumor lysis. However, recent data suggest that uric acid may be an important factor in the pathogenesis of AKI in general, as well as of chronic kidney disease (CKD) and hypertension. Hence, uric acid may not only be a marker but also a potential therapeutic target in kidney disease. Nonetheless, because of confounders, more studies are needed to clarify the association between uric acid and multifactorial disorders of the kidney.

Contribution of the blood glucose level in perinatal asphyxia

This is a comparative study between 60 asphyxiated newborns (cases) and 60 normal neonates (controls) in respect of their plasma glucose and uric acid levels and also their clinical and neurological status. The mean plasma glucose level was significantly lower (35.1 +/- 11.4 mg/dl vs. 56.9 +/- 5.5 mg/dl; P < 0.001) and the mean serum uric acid level was higher (8.0 +/- 1.2 mg/dl vs. 4.5 +/- 0.83 mg/dl; P < 0.001) in the asphyxiated group when compared to the controls. Within the perinatal asphyxia group, the plasma glucose level and Apgar scores showed a significant positive linear correlation (r = 0.740, P < 0.001), whereas a significant negative linear correlation was observed between the glucose level and different stages of hypoxic ischemic encephalopathy (HIE) (r = -0.875, P < 0.001). Although a strong positive linear correlation was found between uric acid and HIE stages (r = 0.734, P < or = 0.001), the linear correlation between uric acid and Apgar scores (r = -0.885, P < 0.001) and uric acid and the plasma glucose level (r = -0.725, P < 0.001) were found to be significantly negative among the cases.

CONCLUSION

The severity of encephalopathy and cellular damage varies with the severity of hypoglycemia.

Correlation between Apgar score and urinary uric acid to creatinine ratio in perinatal asphyxia

A randomized case control hospital based study was conducted over 12 months time on 31 asphyxiated and 31 normal newborn to see whether urinary uric acid can be used as a marker of perinatal asphyxia and can be correlated with the clinical diagnosis by Apgar score. Uric acid and creatinine were estimated in spot urine within 24 hours after birth in both cases and controls. A ratio between concentrations of uric acid to creatinine was estimated and compared between cases and controls. It was found that the ratios were significantly higher in cases than controls (3.1± 1.3 vs 0.96± 0.54; P < 0.001) and among asphyxia patients, a significant negative linear correlation was found between the uric acid to creatinine ratio and the Apgar score (r = -0.857, P < 0.001). So urinary uric acid to creatinine ratio can be used as an additional non-invasive dispace, easy and at the same time early biochemical marker of birth asphyxia which biochemically supports the clinical diagnosis and severity grading of asphyxia by Apgar score.

Value of biochemical markers for outcome in term infants with asphyxia

The aim of this study was to define the predictive values of serum and cerebrospinal fluid concentrations of interleukin-6 and neuron-specific enolase and urinary uric acid/creatinine ratio for outcome in term infants with perinatal asphyxia. All biochemical markers were measured simultaneously within the 24-72 hours of life in 21 infants. The infants were monitored with a standardized neurologic and developmental evaluation protocol over the 2 years of life. The overall outcome at 2 years of age was categorized as "favorable" or "adverse". According to Sarnat and Sarnat classification, 12 infants had mild encephalopathy and 9 infants had moderate to severe encephalopathy. Seven of 9 (78%) infants with moderate to severe encephalopathy had adverse outcome. However, all infants with mild encephalopathy had favorable outcome. Interleukin-6 and neuron specific enolase levels in cerebrospinal fluid and serum interleukin-6 levels were significantly correlated with the degree of encephalopathy, as well as the outcome. Interleukin-6 in cerebrospinal fluid (cutoff value, 25.9 pg/mL) had the highest predictive value among the biochemical markers. The predictive factors identified in this study should be examined for their ability in a fresh clinical sample in the neonatal intensive care unit before these markers can be applied to the routine clinical of infants with perinatal asphyxia.

Measurement of purines in urine by capillary electrophoresis for estimating the degree of hypoxia in infants

We describe a simple, rapid and reproducible method for measuring hypoxanthine, xanthine and uric acid in urine samples of infants by capillary electrophoresis with an uncoated fused silica capillary and ultraviolet detection. Conditions were 40 mmol/l borate buffer pH 9.4 with sodium dodecyl sulphate (0.1 mol) 3 s hydrodynamic load and the voltage 20 kV. The calibration curves for hypoxanthine and xanthine were linear to 150 micromol/l and for uric acid to 300 micromol/l. The limits of detection for hypoxanthine, xanthine and uric acid were 0.5, 2.0 and 20 micromol/l, respectively. Analytical recovery of the three purines ranged from 93 to 105%. Overall CVs were < 5.2%. Using this method, we measured purine concentrations in the urine samples of 103 infants, divided into three groups, according to different degrees of hypoxia. There was a significant difference among the three groups only in hypoxanthine concentrations. In 35 urine samples from the control group, 43 urine samples from infants with a history of an apparent life threatening episode and in 25 urine samples from infants with infantile apnoea, the mean concentrations of hypoxanthine (mean +/- SD) were 13.1 +/- 4.0, 25.1 +/- 8.1 and 58.2 +/- 17.4 micromol/mmol creatinine, respectively. The diagnostic accuracy of the purine measurement was evaluated by receiver-operating characteristic curve analysis.

Value of the urinary uric acid to creatinine ratio in term infants with perinatal asphyxia

The diagnosis of perinatal asphyxia is often inexact and present techniques for assessing its severity are unsatisfactory. The purpose of this study was to describe prospectively the value of the urinary uric acid to creatinine (UA/Cr) ratio in showing increased uric acid excretion in early spot urine samples for the identification of perinatal asphyxia, and to assess the relationship between the urinary UA/Cr ratio and the severity of hypoxic-ischemic encephalopathy. Twenty-seven fullterm infants with perinatal asphyxia were compared with 40 healthy controls. The UA/Cr ratio was higher in the asphyxiated group when compared with controls (2.11 +/- 0.83 vs 0.72 +/- 0.39 P < 0.001). Furthermore, there was a correlation between the UA/Cr ratio and the severity of the encephalopathy (r = 0.84; P < 0.001). The UA/Cr ratio was found to be a good, simple screening test for the early assessment of perinatal asphyxia.

Urinary uric acid excretion in term and premature infants

OBJECTIVE

To clarify postnatal changes in urinary uric acid (UA) excretion in normal term infants and to examine the effects of prematurity or illness on the UA excretion.

METHODOLOGY

Measurements of urinary UA were performed in term and premature infants at the ages of 1 and 7 days and at 1 and 4 months, as well as 7 months in term infants.

RESULTS

Urinary UA levels were lowest on day 7 in term infants. The levels were highest on day 1 in premature infants and remained significantly higher compared to term babies during the first month of life. Respiratory failure requiring ventilation and oxygen supply resulted in further significant elevation of urinary UA in premature infants.

CONCLUSIONS

With the reference values obtained in the study reported here, urinary UA can now be used for the diagnosis and monitoring of inherited disorders of purine metabolism and for the assessment of oxygen radical insult to sick infants.