Serum creatinine during physiological perinatal dehydration may estimate individual nephron endowment.

It is well known that the nephron endowment of healthy subjects is highly variable and that individual nephron mass has potentially important implications both in health and disease. However, nephron count is technically impossible in living subjects. Based on the observation of an increase in serum creatinine (sCr) in otherwise healthy newborns with solitary kidney during the physiological perinatal dehydration, we hypothesized that perinatal sCr might be helpful in identifying healthy subjects with a reduced nephron mass. In the framework of a study on blood pressure in babies (NeoNeph), sCr of normal Caucasian neonates was determined 48-96 h after birth and their association with a family history of arterial hypertension (AH) was analyzed. SCr was determined in 182 normal newborns (90 males) at a mean of 61 ± 8 h after birth (range 46-82). Newborns with paternal AH had a higher mean sCr (0.97 + 0.28 mg/dL) then newborns without paternal AH (0.73 + 0.28 mg/dL; p = 0.006). No differences in mean sCr were found in relation with mother or grandparent's history of AH. CONCLUSION: The association between parental AH and high sCr during perinatal dehydration supports the hypothesis that the latter is a promising tool for identifying normal subjects with a reduced nephron mass with potential important implications in prevention and in understanding the individual outcome of renal and extrarenal diseases (including AH). What is Known: • Nephron endowment of healthy subjects is highly variable and individual nephron mass has potentially important implications both in health and disease however nephron count is not feasible in living subjects. What is New: • Serum creatinine during perinatal dehydration is a possible biomarker for identifying normal subjects with a reduced nephron mass.

Congenital central diabetes insipidus and optic atrophy in a Wolfram newborn: is there a role for WFS1 gene in neurodevelopment?

BACKGROUND: Wolfram syndrome (WS) is an autosomal recessive neurodegenerative disorder characterized by diabetes mellitus (DM), optic atrophy (OA), central diabetes insipidus (CDI) and deafness (D). The phenotype of the disease has been associated with several mutations in the WFS1 gene, a nuclear gene localized on chromosome 4. Since the discovery of the association between WFS1 gene and Wolfram syndrome, more than 150 mutations have been identified in WS patients. We previously described the first case of perinatal onset of Wolfram syndrome newborn carrying a segmental uniparental heterodysomy affecting the short arm of chromosome 4 responsible for a significant reduction in wolframin expression. Here we review and discuss the pathophysiological mechanisms that we believe responsible for the perinatal onset of Wolfram syndrome as these data strongly suggest a role for WFS1 gene in foetal and neonatal neurodevelopment. CASE PRESENTATION: We described a male patient of 30 weeks' gestation with intrauterine growth restriction and poly-hydramnios. During the first days of life, the patient showed a 19% weight loss associated with polyuria and hypernatremia. The presence of persistent hypernatremia (serum sodium 150 mEq/L), high plasma osmolarity (322 mOsm/L) and low urine osmolarity (190 mOsm/l) with a Uosm/Posm ratio < 1 were consistent with CDI. The diagnosis of CDI was confirmed by the desmopressin test and the brain magnetic resonance imaging (MRI) at 34 weeks of age, that showed the lack of posterior pituitary hyperintense signal. In addition, a bilateral asymmetrical optic nerve hypoplasia associated with right orbital bone hypoplasia was observed, suggesting the diagnosis of WF. During the five years follow-up the patient did not developed glucose intolerance or diabetes mellitus. By the end of the second year of life, primary non-autoimmune central hypothyroidism and mild neurodevelopment retardation were diagnosed. CONCLUSIONS: The analysis of our case, in the light of the most recent literature, suggests a possible role for WFS1 gene in the development of certain brain structures during the fetal period. Wolfram syndrome should be considered in the differential diagnosis of the rare cases of congenital central diabetes insipidus developed in the neonatal period.