Diabetes Insipidus and SIADH Charnelle Lee RN, MSN

Diabetes Insipidus Hyposecretion of ADH Description – Insufficiency or hypofunction of antidiuretic hormone (ADH) – ADH stimulates kidney tubules to be permeable to water, so that water is reabsorbed back into the bloodstream – Inadequate ADH means that large quantities of dilute urine are passed Hypotension and hypovolemic shock

Diabetes Insipidus Hyposecretion of ADH Etiology – 3 types Central DI – Primary – Secondary Nephrogenic DI Psychogenic DI

Diabetes Insipidus Hyposecretion of ADH Assessment and Diagnosis – Urine Urine output may be > 300 ml/hr Low urine osmolality Urine is “insipid” or tasteless (not sweet) – Laboratory Tests Serum osmolality Urine osmolality Sodium Serum ADH

Central ADH deficit Neurosurgery, TBI, tumors, Increased ICP, brain death, infections Nephrogenic Kidneys ignore ADH Kidney disease, drugs such as lithium Psychogenis Rare form of DI Compulsive water drinking up to 5 liters/day Types of Diabetes Insipidus

Pathophysiology ADH deficit Excessive diuresis Increased serum osmolarity Hypernatremia Hypovolemic shock

Polyuria without Diuretics Fluids hyperglycemia Diagnosis Assess underlying cause Replace ADH Pituitary dysfunction Treat the reason ADH is not indicated Increased ICP

DI + Laboratory Studies Sodium Level above 145 mEq/L Osmolarity greater than 320 mOsm/L Low Urine osmolarity < 300 mOsm/L Serum Osmolarity Urine Osmolarity

Diabetes Insipidus Hyposecretion of ADH Medical Management – Diagnose and treat cause of DI – Medications to manage Central DI Vasopressin (Pitressin) DDAVP Lypressin – Medications to manage Nephrogenic DI Thiazide diuretics

Diabetes Insipidus Hyposecretion of ADH Nursing Management – Fluid status – Laboratory studies – ADH replacement – Elimination issues – Patient education

Syndrome of Inappropriate Secretion of ADH (SIADH) Hyper-secretion of ADH Description – Opposite of DI – Too much ADH – Kidneys reabsorb too much water – Dilutional hyponatremia

Syndrome of Inappropriate Secretion of ADH (SIADH) Hyper-secretion of ADH Etiology – Head / CNS injury – Malignant bronchogenic oat cell carcinoma – Other conditions – PEEP with mechanical ventilation

Pathophysiology – ADH released by posterior pituitary gland – ADH regulates water and electrolyte balance – Excessive ADH Overhydration Low sodium (dilutional) Concentrated urine Syndrome of Inappropriate Secretion of ADH (SIADH) Hyper-secretion of ADH

Assessment and Diagnosis – Clinical presentation in SIADH relates to water and sodium imbalance – Lethargy – Anorexia – Mental confusion – Seizures, coma, death Syndrome of Inappropriate Secretion of ADH (SIADH) Hyper-secretion of ADH

Assessment and Diagnosis – Serum Laboratory Values Serum ADH Serum Osmolality – Urine Laboratory Values Serum Sodium Urine Osmolality Urine Specific Gravity Syndrome of Inappropriate Secretion of ADH (SIADH) Hyper-secretion of ADH

Medical Management – Secondary disease – Fluid restriction – Sodium replacement – Medications Stop drugs that may cause SIADH Vasopressin receptor antagonists Syndrome of Inappropriate Secretion of ADH (SIADH) Hyper-secretion of ADH

Nursing Management – Hydration status Fluid restriction – Neurologic status – Parental therapy – Patient education Syndrome of Inappropriate Secretion of ADH (SIADH) Hyper-secretion of ADH

Summary (Cont.) Pituitary: DI and SIADH – Central DI occurs when ADH is not released from the posterior pituitary gland. Excretion of large quantities of hypotonic urine creates alterations in serum and urinary laboratory values. – SIADH occurs when excess ADH is released from the posterior pituitary gland. This stimulates kidney tubules to retain water, resulting in fluid overload and hyponatremia manifested by alterations in serum and urinary laboratory values. Copyright © 2014, 2010 by Mosby, an imprint of Elsevier Inc. 19