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Difficulty: EasyEndocrine and Metabolic Mechanisms

Match the following core endocrine disorders with their characteristic laboratory and metabolic findings.

  • Primary hyperparathyroidismHypercalcemia, hypophosphatemia, and inappropriately elevated parathyroid hormone
  • Syndrome of inappropriate antidiuretic hormone (SIADH)Euvolemic hypotonic hyponatremia with elevated urine osmolality
  • Primary adrenal insufficiencyHyponatremia, hyperkalemia, and non-anion gap metabolic acidosis
  • Central diabetes insipidusHypernatremia, elevated serum osmolality, and inappropriately dilute urine

Answer

Primary hyperparathyroidism pairs with hypercalcemia and hypophosphatemia; SIADH pairs with euvolemic hyponatremia; Primary adrenal insufficiency pairs with hyponatremia and hyperkalemia; Central diabetes insipidus pairs with hypernatremia and dilute urine.
Each correct pairing links an endocrine disorder directly to its primary physiological consequence. PTH regulates calcium and phosphate. ADH regulates free water, where an excess (SIADH) causes dilutional hyponatremia and a deficiency (diabetes insipidus) causes hypernatremia. Aldosterone regulates sodium, potassium, and hydrogen, so its absence in primary adrenal insufficiency causes hyponatremia, hyperkalemia, and acidosis.

Step-by-Step Solution

1
Identify the primary hormone derangement for each condition.
Established that primary hyperparathyroidism is excess PTH, SIADH is excess ADH, primary adrenal insufficiency is deficient cortisol/aldosterone, and central diabetes insipidus is deficient ADH.
Understanding the core hormonal defect is required to predict the downstream metabolic effects.
2
Correlate the specific hormonal defect with its expected electrolyte pattern.
Matched PTH excess to calcium/phosphate changes, ADH abnormalities to sodium/water balance, and aldosterone deficiency to potassium/acid-base changes.
Applying basic endocrine physiology directly maps the condition to the laboratory findings.

Key Concept

Classic laboratory patterns of fundamental endocrine disorders
Estimated Time:1m 0s
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Topics

Endocrine and Metabolic Mechanisms

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