Elevated Plasma Sodium and Associated Conditions

• Dehydration – Excess water loss relative to sodium intake leads to higher plasma sodium levels.
• Diabetes Insipidus – Inadequate antidiuretic hormone (ADH) action results in free water loss and hypernatremia.
• Endocrine Disorders – Disorders affecting ADH regulation or salt handling may result in elevated sodium levels, sometimes in the setting of autoimmune hypothalamic dysfunction.

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Low Plasma Sodium and Associated Conditions

• Excess Fluid Retention or Overhydration – Conditions like congestive heart failure, liver cirrhosis, or syndrome of inappropriate ADH secretion (SIADH) lead to dilutional hyponatremia.
• Renal Salt Wasting – Some renal or autoimmune conditions (such as interstitial nephritis) may impair sodium reabsorption.
• Medications – Diuretic therapy and other drugs may precipitate low sodium levels.

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Plasma Sodium Across Life Stages

• Infants – Have a narrower margin for sodium imbalances, requiring careful monitoring.
• Older Adults – Especially those with chronic comorbidities, are more prone to both hyper- and hyponatremia due to altered water and salt homeostasis.

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Electrolyte and Mineral Markers

This group of markers evaluates essential ion and mineral levels in the blood, each playing a critical role in maintaining physiological balance:

• Blood Phosphorus: Reflects circulating phosphate levels, crucial for bone health and energy metabolism, influenced by renal excretion and hormonal control.
• Plasma Potassium: Indicates the concentration of potassium, vital for proper nerve function and muscle contraction.
• Plasma Sodium: Measures the main extracellular ion responsible for osmotic balance and fluid distribution.
• Serum Calcium: Reveals calcium levels that support neuromuscular activity, cellular signaling, and bone health.
• Serum Magnesium: Assesses magnesium status, important for enzymatic reactions and muscle and nerve function.
• Lithium: Although primarily of therapeutic interest, its circulating levels interact with water and electrolyte balance, mirroring renal handling similar to other electrolytes.

Together, these markers provide a comprehensive view of the body's mineral balance and electrolyte function.

Hormonal Regulators of Electrolytes and Minerals

• Parathormone (PTH) adjusts calcium and phosphate levels via its influence on bone resorption and kidney reabsorption
• Antidiuretic Hormone (ADH) modulates water reabsorption in the kidneys to indirectly control plasma sodium levels and overall fluid balance. Together, these markers provide a

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