DI, SIADH, and Thyroid disorders

• Disorder of sodium and water balance is a common complication following neurosurgery. Early detection is critical to the protection of the brain.


  Syndrome of inappropriate antidiuretic hormone (SIADH)
• Normal brain regulation

  20% ECF

  40% ICF
• Total body water?

  60% of body weight
• sodium and potassium (Na&K)


  What are the principal determinants in fluid shifts
• Osmolarity 


  Amount of solute in fluid (urine, blood)
• 270-295mOsm/L


  Normal serum osmolarity?
• Water deficit


  Serum Osmolarity above 295 mOsm/L
• water excess

  Serum osmolarity is below 270 mOsm/L
• Antidiuretic hormone 


  It balances Na and water in body, controlling it's water conservation
• triggers release of ADH from Pituitary gland

  Changes in pressure of ECF
• Antidiuretic hormone


  also called as Vasopressin and causes vasoconstriction
• Presence of ADH


  Renal tubule permeability to water is increased and water is reabsorbed
• Absence of ADH

  Renal tubule permeability to water is decreased, therefore there is increased renal excretion to fluids.
• Plasma osmolality


  primary regulatory mechanism for the release of ADH
• 135 to 145


  Normal Na serum
• Pituitary gland


  The organ that stores ADH
• Hypothalamus


  ADH is produced by?
• SIADH


  Injury in the pituitary gland and hypothalamus is at risk of?
• Delusional hyponatremia


  Excess increases fluid volume, increasing also the ICP
• Treatment for SIADH:

  • Correct underlying cause
  • Fluid restriction of 500-1000 ml/day
  • Severe hyponatremia: 3% NSS may be given (Na)
  • Lasix may be given to decrease fluid volume (watch K

  level because Lasix can also cause loss of potassium)
• Serum Na Level

  145-135 mEq/L Normal concentration, no symptoms

  135-120 mEq/L Generally no changes

  120-110 mEq/L Headache, apathy, lethargy, weakness, disorientation, thirst, fatigue, seizures

  110-100 mEq/L Confusion, hostility, lethargy, N/V, abdominal cramps, muscle twitching

  100-95 mEq/L Delirium, convulsions, coma, hypothermia, areflexia, Cheyne-Stokes respirations, death
• SIADH


  Persistent abnormally high (inappropriate) levels of ADH in the absence of stimuli with normal renal function
• DI

  Disordered regulation of water balance due to impaired urinary concentrating ability secondary to inadequate secretion of ADH or resistance to ADH.
• Diabetes Insipidus

  S&S: Polyuria

  • USG low (below 1.005)
  • Polydipsia
  • Signs of dehydration (Low BP, increased heart rate, dry mucus membrane)
  • Hypernatremia (Na) [higher than 145 mEq/L]
• SIADH

  S&S: Oliguria

  • USG High (higher than 1.030)
  • Edema + weight gain
  • Hyponatremia (Na) [cerebral edema, seizures, coma] - lower than 135 mEq/L
• Risk factors of SIADH

  Post-operative with pituitary surgery

  Acute head injury

  Pneumonia

  meningitis
• Risk factors of DI

  Head injury

  Neurosurgery

  Hypothalamic, pituitary, & brain tumors

  Brain infection/inflammation

  Increased ICP

  Stroke

  Hypoxia

  Medications (Dilantin, clonidine, alcohol)
• Lab test for SIADH

  • Serum Na – less than 135 mEq/L
  • Urine Na – greater than 20 mEq/L
  • Urine Osmolality – Above 900 mOsm/kg
  • Serum Osmolality – less than 275 mOsm/L
  • Urine Specific Gravity – greater than 1.005
  • Serum Potassium – less than 3.5 mEq/L
• Lab test for DI

  • Serum Na – More than 145 mEq/L
  • Urine Na – greater than 145 mEq/L
  • Urine Osmolality – below 300 mOsm/L
  • Serum Osmolality – more than 290 mOsm/L
  • Urine Specific Gravity – below than 1.005
• Treatment of DI

  • Correct the underlying cause and maintain adequate fluid replacement because patient will have dehydration
  • DI Therapy varies with the degree and type of DI present or suspected.
  • IVF may be necessary to correct hypernatremia; avoid rapid replacement
  • Free from water restriction
  • After assessing fluid status and serum sodium level, treat both dehydration and hypernatremia
  • Consultation with an endocrinologist is highly recommended
• Complications to treatments of DI and SIADH

  • Cerebral edema, in DI there's dehydration so bibigyan ng IVF therapy, if mag excess this will lead to this complication.
  • S/S but not necessarily immediate.
  • Acute paralysis
  • Dysphagia (swallowing difficulties)
  • Dysarthria (weak speech muscle)
• Most important nursing intervention for SIADH and DI

  • Frequent labs
  • Observe of electrolyte abnormalities
  • Na should not rise more than 0.5mEq/L/hr and 10mmol/L/24hrs
  • Frequent Neuro assessment
  • note any changes from the baseline
• Butterfly shaped located at the base of the neck justbelow the adam's apple which is about 4-6 cm indiameter and 2-3 inches in length


  Thyroid gland
• to regulate growth and metabolism;it regulates how the body uses energy by stimulating almost every tissue in the body to produce protein, also by increasing the amount of oxygen that the cells use

  Thyroid gland
• T3 (Triiodothyronine)


  Metabolism and growth
• T4 (Thyroxine, tetraiodothyronine)


  Catabolism and body heat production
• Thyrocalcitonin


  Regulates serum Ca+++ levels and brings down the blood Ca+++ level
• • Normal T3 = 100 to 200 ng/dL
  • Normal T4 = 5 to 12 mcg/dL
  • Normal TSH = 0.5 to 5 miu/L
• Preparation: no foods, drugs, test dyes with iodine

  7-10 days before the test


  PBI (Protein-Bound Iodine)
• Enlargement of the thyroid gland associated with hyperthyroidism (↑ T3 T4), hypothyroidism (↓ T3 T4) or euthyroidism (normal T3 T4)

  Goiter