Chapter 26: Clinical Biochemistry at the Extremes of Age

In neonatal care, the text defines developmental milestones for preterm infants and highlights the critical limitations of blood volume and renal immaturity, where a reduced glomerular filtration rate and inefficient tubular function necessitate precise monitoring of fluid and electrolyte homeostasis, particularly sodium and potassium levels. Respiratory health is explored through conditions like respiratory distress syndrome and surfactant deficiency, while metabolic challenges such as neonatal jaundice and hyperbilirubinemia are analyzed for their risk of causing neurological damage like kernicterus. The discussion extends to glucose metabolism, identifying risks for hypoglycemia in infants with low glycogen stores or inborn errors of metabolism, and examines bone health through the lens of neonatal hypocalcemia and rickets of prematurity. Transitioning to geriatric medicine, the chapter emphasizes the clinical complexity of treating older adults who often present with multiple pathologies and the risks associated with polypharmacy. Key age-related changes are detailed, including the decline of renal clearance and the increased prevalence of metabolic disorders such as type 2 diabetes, thyroid dysfunction, and skeletal diseases like osteoporosis and Paget's disease. Finally, the text underscores the importance of distinguishing between neurodegenerative conditions like Alzheimer’s disease and treatable causes of dementia, such as nutritional deficiencies or hypothyroidism, to ensure accurate diagnosis and management in aging populations.