Metabolic Abnormalities

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Metabolic Abnormalities

• Surgical Fundamentals Lecture
• Asha Bale, MD
• 8/06/10

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Overview

• Symptoms, Etiology, Treatment
• Sodium
• Potassium
• Magnesium
• Calcium
• Glucose abnormalities
• Arrhythmias

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Hyponatremia Nalt136

• Most Common causes are Iatrogenic or SIADH
• Sx CNS (increased ICP)
• Sx usually dont occur until Nalt120
• Causes
• Na depletion (extracellular volume deficit)
• Na dilution (Excess extracellular water)
• Excess solute relative to free water (ie
  hyperglycemia)
• Pseudohyponatremia

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Na depletion

• Decreased intake
• Low sodium diet
• Enteral feeds
• Loss of Na containing fluids
• GI losses (vomitting, NGT, diarrhea)
• Renal losses (diuretics or primary renal disease)

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Na Dilution

• Excess extracellular water/Excess extracellular
  volume
• Iatrogenic (IVF, free water)
• High ADH (increases reabsorption of free water,
  causing increase in volume and hypoNa)
• SIADH- low serum Na, high Urine Na and U Osm
• Drugs causing water retention
• Antipsychotics, tricylcic antidepressants, ACE
  inhibitors

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Excess solute causing HypoNa

• Excess solute relative to free water can cause
  hyponatremia
• Untreated hyperglycemia
• Glucose causes an osmotic force, shifting water
  from the Intracellular compartment to the
  Extracellular compartment (like dilutional
  hypoNa)
• For every 100mg/dl increase in Glu, plasma Na
  decreased by 1.6
• Mannitol

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Pseudohyponatremia

• Extreme elevations in plasma lipids and proteins
• No true decrease in extracellular sodium relative
  to water

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Hyponatremia Algorithm

• Symptomatic or Asymptomatic?
• Asymptomatic
• Hypotonic (POsmlt280)
• Hypervolemic- water restriction, diuresis
• Hypovolemic- isotonic saline
• Isovolemic- water restriction
• Isotonic (POsm 280-285, hyperlipidemia)
• Correct underlying disorder
• Hypertonic (POsmgt280, hyperglycemia, hypertonic
  infusions like mannitol)
• Correct underlying disorder
• Symptomatic (treat aggressively)
• 3 NaCl
• Dont correct fast!
• Stop when Na 120-125

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Treatment of Hyponatremia

• Water deficit(L) (serumNa-140 / 140) x TBW
• TBW estimated as 50 of lean body mass in men and
  40 in women
• Dont correct faster than 1mEq/h and 12mEq/d,
  avoids cerebral edema and herniation
• Frequent neurologic exams

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Treatment of Hyponatremia

• Most cases- Free water restriction, if severe-
  administer sodium
• If Neuro Sx, then use 3 NS to increase Na by no
  more than 1mEq/L per hour until Na level reaches
  130, or Neuro Sx are inproved
• Rapid correction causes pontine myelinosis,
  seizures, death

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Hypernatremia Nagt144 mEq/L

• Caused by loss of water or a gain in Na in excess
  of water (hypervolemic, isovolemic, hypovolemic)
• Can be assoc with increased, normal or decreased
  extracellular volume
• Water shifts from ICF to ECF, causing cellular
  dehydration
• Sx (neurologic) restlessness, irritability,
  seizures, coma, death

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Hypervolemic Hypernatremia(Gain of water and
salt)

• Iatrogenic
• Administration of Na containing fluids, including
  Na Bicarb
• Mineralocorticoid excess
• U Nagt20meq/L, Uosmgt300mOsm/L
• Hyperaldosteronism
• Cushings Syndrome
• Congenital Adrenal Hyperplasia

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Normovolemic Hypernatremia(Loss of water)

• Nonrenal Causes of water loss
• GI
• Skin
• Renal Causes of water loss
• Diabetes Insipidus
• Diuretics
• Renal Disease

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Hypovolemic Hypernatremia(Loss of water and salt)

• Renal water loss
• DI (Low ADH) (high Serum Na, dilute urine, low U
  Na and U Osm)
• Osmotic diuretics
• Adrenal failure
• Renal tubular diseases (UNalt20, UOsmlt300-400)
• Nonrenal water loss (GI, Skin)
• UNalt15, UOsm gt400)

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Hypernatremia Algorithm

• History, physical, electrolytes, BUN/Creatinine,
  Urine Na, UOsmolarity
• Assess extracellular volume status
• Hypovolemic (Loss of water and Na)
• Restore extracellular volume, calculate water
  deficit
• Isotonic saline until euvolemic, then hypotonic
  saline or D5W to correct HyperNa
• Isovolemic (Loss of water)
• D5W IV or water p.o.
• Diabetes Insipidus- Vasopressin
• Hypervolemic (Gain of Na and water)
• Lasix and D5W or D51/4 NS
• If renal failure? dialysis

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Hyperkalemia

• Normal K 3.5 to 5.0 meq/L
• History, physical, EKG, chemistry, ABG
• Sx GI (n/v, diarrhea), neuromuscular (weakness),
  cardiovascular (EKG changes, arrhythmias)
• EKG changes
• Peaked t waves
• Flattened p wave
• Prolonged PR interval
• Widened QRS complex
• Sine wave formation
• V-fib

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Hyperkalemia EKG Peaked t wavesFlattened p
waveProlonged PR intervalWidened QRS
complexSine wave formationV-fib
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Hyperkalemia

• Excess Potassium Intake
• Oral, iv, blood transfusion
• Increased Release of K from cells
• Cell destruction/breakdown
• Hemolysis, rhabdomyolysis, crush injuries, GI
  hemorrhage, acidosis
• Impaired excretion by kidneys
• Meds K sparing diuretics, ACE Inhibitors,
  NSAIDs
• Renal Insufficiency, Renal Failure

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Treatment of Hyperkalemia

• Reduce total body K
• Stop exogenous sources of K
• Kayexalate
• (Cation-exchange resin, binds K in exchange for
  Na)
• PO or PR
• Dialysis
• Shift K from extracellular to intracellular
• Glucose/Insulin, bicarbonate
• Albuterol
• Protect cells from effects of increased K
• When EKG changes present, use Calcium chloride or
  calcium gluconate (5-10mL of 10 solution)
• Use cautiously in patients on Digoxin- can cause
  Dig toxicity

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Hyperkalemia Algorithm

• History, PE, EKG, Chemistry, ABG
• Klt6.5, no EKG changes?
• Stop supplemental K and repeat K
• Klt6.5, EKG changes?
• Stop K, Kayexalate or Lasix, look for underlying
  cause
• Kgt6.5 or EKG changes?
• Calcium gluconate, Glucose Insulin, NaHCO3,
  Kayexalate, Lasix, Dialysis

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Hypokalemia

• Klt3.5 mg/L
• Sx
• Ileus, constipation
• Weakness, fatigue
• Cardiovascular
• EKG changes u waves, t wave flattening, ST
  segment changes, arrhythmias

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Etiology-Hypokalemia

• Inadequate intake
• Dietary, K free IVF, TPN with inadequate K
• Excessive Renal Excretion
• Hyperaldosteronism (waste K)
• Meds
• Diuretics which increase K excretion
• Penicillin (promotes renal tubular loss of K)
• Loss in GI Secretions
• Diarrhea, vomiting, high NGT outputs

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Etiology- Hypokalemia

• Intracellular shifts
• Metabolic Alkalosis
• K decreases by 0.3 mEq/L for every 0.1 increase
  in pH above normal
• Insulin therapy
• Drugs causing Magnesium depletion will cause K
  depletion as well
• Amphotericin, aminoglycosides, foscarnet,
  cisplatin
• Replace Magnesium!

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Treatment of Hypokalemia

• Check K, electrolytes, renal function and urine
  output
• Estimate for every 10 mEq K replaced, the serum
  potassium will increase by 0.1 mg/L
• Potassium repletion
• Oral (functioning GI tract, mild, asymptomatic
  patients)
• KCl, K-dur
• IV (Nonfunctioning GI tract, or severe
  hypokalemia)
• No more than 20meq/H in an unmonitored setting
• Can be up to 40meq/h replacement in monitored
  setting
• Caution in patients with impaired renal function
• Repeat K levels
• KCl, KPhos

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Magnesium Abnormalities

• Magnesium found in the intracellular compartment
• Of that found in the extracellular space, 1/3 is
  bound to albumin
• Normal 1.3 to 2.1 mEq/L

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Hypermagnesemia Mg gt2.2 mEq/L

• Rare
• Impaired renal function, excess intake with TPN,
  Excess use of laxatives or antacids
• Sx n/v, weakness, lethargy, hypotension
• EKG changes (similar to hyperkalemia)
• Increase PR interval, widened QRS complex,
  elevated t-waves
• Tx Ca 100-200mg IV over 5-10 mins., Dialysis,
  Remove Magnesium source

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Hypomagnesemia

• Renal excretion
• Alcoholism, diuretics, Amphotericin B
• GI Losses
• Diarrhea, malabsorption, acute pancreatitis, DKA,
  primary hyperaldosteronism
• Poor p.o. intake
• Starvation, alcoholism, prolonged use of IVF, TPN

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HypoMagnesemia

• Sx neuromuscular and CNS hyperactivity, tremors,
  delerium, seizures
• Sx similar to hypercalcemia
• Associated with hypokalemia
• EKG
• Prolonged QT and PR intervals
• ST segment depression
• Flattened or inversion of p waves
• Torsades de pointes
• arrhythmias

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Torsades de Pointes- hypomagnesemia
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Treatment of Hypomagnesemia

• Oral replacement if mild or asymptomatic
• Magnesium Oxide
• IV replacement if severe (lt1.0 mEq/L) or
  symptomatic
• 2g Magnesium sulfate IV over 5 minutes followed
  by 10g during the next 24 hours (if renal
  function is normal)
• If Torsades, give over 2 mins.
• Also correct hypocalcemia, frequently associated

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Hypercalcemia Cagt10.5

• Serum Ca above normal range of 8.5 to 10.5 mEq/L,
  or an increase in the ionized calcium level above
  4.2 to 4.8 mg/dL
• Primary hyperparathyroidism (outpatient)
• Malignancy (inpatient)
• Sx Neuro (confusion, depression), Musc
  (weakness, back pain), GI (n/v/ abd pain),
  cardiac, EKG changes

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Hypocalcemia prolongs the QT interval by
stretching out the ST segment. Hypercalcemia
decreases the QT interval by shortening the ST
segment so that the T wave seems to take off from
the QRS complex
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Treatment of Hypercalcemia

• Most cases due to malignancy, if not check PTH
  level
• PTH high? hyperparathyroidism
• PTH normal or low? w/u for malignancy
• Treatment is supportive, treat underlying cause
• Tx when symptomatic (Hypercalcemic crisis)
  (serum level gt12mg/dL)
• Replete volume deficit, then brisk diuresis with
  normal saline and Lasix
• 1-2L NS over 1-2h, followed by 200-400mL/h with
  Lasix 20-80mg IV over 2-3h
• Etidronate, phosphate, Mithramycin, steroids,
  Calcitonin, Dialysis

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Hypocalcemia

• Etiologies pancreatitis, massive soft tissue
  infections, renal failure, pancreatic and SB
  fistulas, hypoparathyroidism, Magnesium
  abnormalities, tumor lysis syndrome
• Transiently after removal of a parathyroid
  adenoma
• Malignancies assoc w/ increased osteoclastic
  activity
• Massive blood transfusions (precipitation with
  citrate)
• Sx parasthesias, muscle cramps, stridor, tetany,
  seizures

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Treatment of hypocalcemia

• Check albumin, check for abnormalities of Phos
  and Mag
• Asymptomatic- give po or iv
• Chronic
• Add Calcium to IVF
• Calcium p.o. (1500 to 3000mg per day, plus
  vitamin D)
• Acute symptomatic
• Need to give 200 to 300mg of Calcium
• 20-30mL 10 Ca Gluconate OR
• 5-10mL 10 Ca Chloride
• Give slowly over several minutes
• Can worsen HTN or Dig toxicity
• Correct associated deficits in magnesium,
  potassium and pH

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HyperphosphatemiaSerum Phos gt5mg/dL

• Normal 2.7 to 4.5 mg/dL
• Mostly seen in pt with renal failure
• Hypoparathyroidism
• Tx
• Chronic- Low Phos diet, aluminum binding antacids
• Acute- Dialysis

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Hypophsphatemia

• Decreased intake
• Intracellular shift of phosphorus
• alkalosis, insulin therapy
• Increased phosphorus excretion
• Sx muscle weakness (important for vent dependent
  pts)
• PO- Nutraphos
• IV- NaPhos, KPhos

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Arrythmias

• Ask Desk Clerk to CALL Senior Resident and/or
  Attending!
• Symptomatic or Asymptomatic?
• ABCs
• Code Cart into room, call Anesthesia if needed
• Vital signs, O2 Sat
• Quick History/Physical Exam
• EKG/Rhythm strip- Recognize the Arrhythmia
• Place on a monitor, Supplemental Oxygen
• ACLS Protocol- Stabilize Patient
• ABG or ABE, electrolytes, cardiac enzymes
• Treat Underlying Cause

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Arrhythmia
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Arrhythmia
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Arrhythmia A-Fib
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Arrhythmia
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Arrhythmia SVT
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Arrhythmia
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Arrhythmia V-Tach
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Arrhythmia
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Arrhythmia