General Internal Medicine Electric-Lytes Dr. Jeffrey P Schaefer General Internal Medicine 1

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Objectives Case based approach to abnormal Sodium Potassium Calcium Magnesium Phosphate

Sodium

Warm Up Case 81 yr old female presents to ER recent viral illness vomiting and diarrhea Na  125 mmol/l

What are the clinical features of hyponatremia?

Hyponatremia Neuromuscular Irritability mild anorexia headache muscle cramps irritability delirium coma seizure Rate of Reduction affects clinical severity

What are the causes of hyponatremia?

Common Causes Volume Depletion Edema Water excess Salt loss diuretics (esp thiazide), vomiting, diarrhea Edema heart failure, nephrosis, cirrhosis Water excess SIADH, polydipsia, iatrogenesis Salt loss hypoadrenal, hypoT4, cerebral salt wasting Shift (pseudohyponatremia) hyperglycemia, hyperlipidemia

Case 81 yr old female presents to ER malaise recent viral illness vomiting and diarrhea Na = 125 mmol/l

How should this case be managed?

Orders Solution? Volume? Rate(s)? Reassess?

Orders Solution? Volume? Rate(s)? Reassess? Normal Saline 1 – 4 l according to clinical assessment 250 – 500 / hr x 1 l, then 100 – 150 ml/hr clinical reassess in 4 – 6 hours recheck lab in 24 hours

Sodium, Salt What’s in Normal Saline? NaCl 154 mmol/l Na 154 mmol + Cl 154 / litre

Sodium, Salt What’s in Normal Saline? Implication for heart failure NaCl 0.9% w/v 0.9 grams solute per 100 grams solvent 0.9 grams salt per 100 grams water 9 grams salt per 1,000 grams water 9 grams salt per 1,000 ml water Normal Saline is NaCl 9 g / l Implication for heart failure Mw(NaCl) = 22.990 + 35.453 = 58.443 g/mol Na accounts for (23/35) ~ 40% weight of salt Low Salt Diet = 2 g of sodium = 1 tsp Low Salt Diet = 2 g / 0.4 = 5 g NaCl Low Salt Diet = 555 ml of normal saline

What Other Flavors of IV Do We Have?

Sodium, Salt, Sugar Na+ mmol/l Dextrose in Water 0 ½ Normal Saline 77 Ringer’s Lactate* 130 Normal Saline 154 Hypertonic Saline 513 * Ringer’s Lactate: Na+ 130 mmol, K+4 mmol, Ca++ 1.5 mmol, Cl− 109 mmol, lactate 28 mmol electrolyte content is isotonic (273 mOsmol/liter) in relation to the extracellular fluid (approx. 280 mOsmol/liter).

Case 82 year old female in ER HTN on thiazide presents with seizure and coma estimated weight 60 kg Na = 105 mMol

How should this case be managed?

Sodium Deficit Calculated sodium deficit *0.6 males x (weight in kg) x (desired sodium - actual sodium) *0.5 for females desired range is 105 mmol/l + 5 mmol/l = 110 mmol/l hypertonic saline has 513 mMol / l of Na

Sodium Deficit *0.5 x (weight in kg) x (desired sodium - actual sodium) *0.5 for females 0.6 for males desired increase = 105 mmol/l + 5 mmol/l = 110 mmol/l 0.5 x 60 kg = 30 l 30 l x 5 mmol/l = 150 mmol hypertonic saline has 513 mMol / l of Na 150 / 514 = 300 ml 300 ml over 1 or 2 hours then reassess OR 100 ml bolus x 10 min, then another, then another... REASSESS CLINICALLY and BIOCHEMICALLY q 1-2h

Rapid Correction of Hyponatremia central pontine myelinolysis risk risk is minimal if increase is 0.5 – 1.0 mmol/h

Case 30 year old female presents to ER was hiking in the mountains drank 10 liters of water per day on the advice of a well meaning friend delirium with paranoia Na = 110 mmol/l ?

Case 78 year old female on general surgery Post-op day 3 hemicolectomy for Duke B ca Overnight developed delirium Post-op IV order: ‘2/3 – 1/3 @ 125 ml/h’ Na = 120 mMol

Case 19 year old man presents to ER progressive weakness anorexia and weight loss nauseated unusually tanned! Na = 128 mMol, K = 6.5 mMol

Case 82 year old female in clinic HTN on thiazide feels well Na = 125 mMol

Case 65 year old man on neurosurgery post-op day 2 brain aneursym clip Na = 129 mMol

Case 59 year old female presents with pneumonia day 4 feels strange can eat and drink, likes tea Na = 120 mMol

SIADH water restriction is mainstay diuretics maybe vaptans... probably not yet

Vaptans ADH antagonist - Tolvaptan (Samsca, Otsuka) in Canada - 15 – 30 mg tablets..... $120 / day - black box warning re: hepatic toxicity

Warm Up Case 81 year old female on stroke unit doing poorly over last few days now unconscious Na = 176 mMol (normal 135-145 mMol)

What are clinical features of hypernatremia?

Clinical Features Hypernatremia lethargy weakness irritability twitching delirium reduced level of consciousness coma seizures ‘neuromuscular irritability’

What are the causes of hypernatremia?

DDx – HyperNa+ Not enough water! no thirst can’t act on thirst can’t retain water except for Normal Saline, not usually a salt issue

Case 81 year old female on stroke unit doing poorly over last few days now unconscious Na = 176 mMol (normal 135-145 mMol) estimated weight 60 kg

Diagnosis? Management? Solution Volume Rate

Solution Na+ mmol/l Dextrose in Water 0 ½ Normal Saline 77 Ringer’s Lactate* 130 Normal Saline 154 Hypertonic Saline 513 * Ringer’s Lactate: Na+ 130 mmol, K+4 mmol, Ca++ 1.5 mmol, Cl− 109 mmol, lactate 28 mmol electrolyte content is isotonic (273 mOsmol/liter) in relation to the extracellular fluid (approx. 280 mOsmol/liter).

Correct no faster than 0.5 – 1 mmol / hr Rate of Correction Correct no faster than 0.5 – 1 mmol / hr Risk of cerebral edema determine water deficit determine duration of correction rate = deficit / duration (index to hour) consider ongoing losses decide on re-assessment

Volume Water Deficit (Na+ measured – 140 mmol/l) 0.6 x kg -------------------------------------- 140 mmol/l use 0.5 for females desired = 140 mMol

Calculate Free Water Deficit (176 mmol / l – 140 mmol/l) 0.5 x 60 x -------------------------------------- 140 mmol/l 7,710 ml 36 mmol / 0.5 – 1.0 mmol/hr = 48 hr 160 ml/hr of ‘free water’ D5W or tube water at 160 ml/hr

Advanced Case 55 year old female pituitary resection post-op dilute polyuria Na = 165 mMol

DDAVP IV / sq  1-2 ug q12 h nasal  10 – 40 ug / day (divide bid / tid) oral  0.1 – 1.2 mg / day (divide bid / tid) give hypotonic IV while getting control usually this is a planned event

Warm Up Case 78 year old presents with sob recent gout indomethacin creatinine 790 K = 7.0 mMol

What are the clinical features of hyperkalemia?

Clinical Features death

What are the causes of hyperkalemia?

Potassium Hyperkalemia: Pseudohyperkalemia acute renal failure pre-renal renal: especially *drugs and toxins (acute!) post-renal too much K ACE-I, ARBs, spironolactone, NSAIDs Pseudohyperkalemia check CBC and phlebotomy

Case 78 year old presents with sob recent gout indomethacin creatinine 790 K = 7.0 mMol

Case Restore renal function Remove K from body Shift K into cells D5-normal-bicarb (3 amps bicarb into 850 ml of D5W kaliuresis  loop diuretic remove obstruction Remove K from body K binder  Resonium or Kayexalate New Kids on the block... sodium zirconium cyclosilcate (ZS-9)and patiromer (Veltassa) laxative Shift K into cells create alkalosis, insulin, glucose, salbutamol Plan for Dialysis (order HBsAg, nephro)

Case General Principles optimize cardiac output mitigate all nephrotoxicity minimize potassium sources

Case 78 year old man with CLL routine blood work WBC = 75,000 x 109/l ECG normal

Case 65 year old man post-op day 4 cholecystectomy NS at 125 ml/hr K = 2.8

What are the clinical features of hypokalemia?

Clinical Features hypokalemia muscle twitch / spasm dysrythmia increase risk of atrial fibrillation

What are the causes of hypokalemia?

Hypokalemia Epidemiological Approach diuretics failure to supplement vomiting (suction) & diarrhea hypomagnesemia amphotericin, platinum based chemotx

Normal and Flat ST

How can potassium be replaced?

Potassium Replacement Oral whenever possible KCl tablet 8 mEq (slow-K, micro-K) KCl tablet 20 mEq (K-Dur) KCl tablet 25 mEq (K-lyte effervescent) KCl solution 10% IV if needed 20 – 40 mMol / l added to IV 10 mMol / hour max

Can hypokalemia be prevented among patients who need diuretics?

Potassium Avoid Kaliuresis you can add / use potassium sparing diuretics

Case 24 year old female presents to ER nausea, vomiting Na = 132 K = 6.8 Cl = 100 HCO3 = 5 glucose = 28

Case Diabetic Ketoacidosis potassium shift

Summary Diagnosis and Treatment: hyponatremia hypernatremia hyperkalemia hypokalemia

Case 58 year old female post-op hour 6 neck surgery twitchy and trouble breathing Calcium = 1.7 mMol (2.15 – 2.30 mMol)

DDx - hypocalcemia In hospital injured parathyroid glands acute pancreatitis uncorrected calcium for albumin

measured Ca + [(40 – alb) x 0.02] Albumin Correction Corrected Ca = measured Ca + [(40 – alb) x 0.02] e.g. albumin is 20 g/l measured Ca = 1.90 mmol correction is  20 x 0.02 = 0.4 1.9 + 0.4 = 2.30 mMol

Case 58 year old female post-op hour 6 neck surgery twitchy and trouble breathing Calcium = 1.7 mMol (2.15 – 2.30 mMol)

Calcium Replacement Oral Preferred IV if emergency Calcium carbonate (500 mg elemental) dose according to situation vit D3  0.25 to 0.5 ug od IV if emergency 10% ca-gluconate 90 mg / 10 ml x 1 to 2 ampules each over 3 – 5 minutes or longer 10% ca-chloride 270 mg / 10 ml (AVOID)

IV Calcium for EMERGENCY 10% Ca-gluconate x 6 amps into 500 ml of D5W = 540 mg / 560 ml = ~ 1 mg/ml 0.25 – 0.50 mg / kg / hour infusion BE CAREFUL – GOOD IV NEEDED MONITOR FREQUENTLY CO-ADMINISTER ORAL AND VIT D so as to GET OFF IV ASAP

Case 59 year old female with breast cancer obtunded Ca = 4.5 mMol

Calcium Hypercalcemia constipation abdominal pain general achiness depressed mood decreased LOC coma

DDx Hypercalcemia Malignancy Hyperparathyroidism Excess Calcium / Vit D Fracture Bed rest

Case 59 year old female with breast cancer obtunded Ca = 4.5 mMol

Calcium Case Calciuresis Bisphosphonate Saline load Furosemide Zoledronic acid (Zometa) Pamidronate, Clodronate

Case 34 year old homeless man presents Feels poorly Day 2 PO4 = 0.20 mMol (0.8 – 1.5 mMol)

Ddx – Hypo PO4

Hypophophatemia Refeeding (> 95%) Hyperparathyroidism diabetic keto-acidosis anorexia enteral or parenteral nutrition Hyperparathyroidism

Case 34 year old homeless man presents Feels poorly Day 2 PO4 = 0.20 mMol (0.8 – 1.5 mMol)

Phosphate Sandoz Phosphate Milk and Food

Case 55 yr old alcoholic blood tests done Mg = 0.8 mMol (1.2 – 2.2 mMol)

Hypomagnesemia Magnesium sulfate 1 to 5 grams IV Per Protocol! hypotension chest tightness flushing Oral is ‘okay’ but can cause diarrhea