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Water and Electrolyte balance and Imbalance

Q.1- A 64 year-old man who develops acute renal failure while recovering from a severe acute myocardial infarction (Acute MI), Blood chemistry reveals:

Na+ 140 mEq/L, K+ 4 mEq/L, Cl115 mEq/L, CO2 5 mEq/L, pH = 7.12, PaCO2 13 mmHg, and HCO34 mEq/L. Calculate the anion gap and then choose the best answer  for acid-base status.

A) His anion gap of 14 indicates he has metabolic alkalosis

B) His anion gap of 20 is conclusive of a respiratory acidosis.

C) His anion gap of 22 strongly suggests a respiratory alkalosis

D) His anion gap of 21 is conclusive of high anion gap metabolic acidosis

E) His anion gap of 25 is conclusive of normal acid base status.

Q.2- A 48-year-old man with bronchiectasis presents to the hospital emergency room with 3 days of increasing cough, sputum, and dyspnea. About 1 month ago, his arterial blood gas analysis showed pH 7.38, PaO2 55 mmHg, PaCO2 65 mmHg, and HCO332 mEq/L. His current vital signs are BP 117/65 mmHg, Pulse 123/min, Temperature 100°F. His current ABG(Blood gas analysis) in the Emergency Room is pH 7.28, PaCO2 70 mmHg, PaO2 50 mmHg, and HCO323 mEq/L. Which of the following best characterizes the current acid-base status?

A) Compensated metabolic acidosis

B) Compensated metabolic alkalosis

C) Uncompensated metabolic acidosis

D) Uncompensated respiratory acidosis

E) Uncompensated respiratory alkalosis

Q.3- A hospital patient with AIDS has diarrhea and becomes hypovolemic within a short period of time. Which of the following laboratory results would best fit this clinical history?

A) pH: 7.15, pCO2: 55 mmHg, HCO3: 40 mEq/L

B) pH: 7.25, pCO2: 36 mmHg, HCO3: 15 mEq/L

C) pH: 7.40, pCO2: 40 mmHg, HCO3: 24 mEq/L

D) pH: 7.50, pCO2: 28 mmHg, HCO3: 24 mEq/L

E) pH: 7.35, pCO2: 40 mmHg, HCO3: 24 mEq/L.

Q.4- A 50-year-old chronic alcoholic is brought to the emergency room in a semiconscious state. Blood pressure is 100/50 mmHg, heart rate 120 beats/min, respiratory rate 35/min, and his temperature is 104F (40C).

Blood chemistry reveals : Sodium 150mEq/L (135-145), Potassium 2.5mEq/L (3.5-5.0), Chloride 107mEq/L (95-105),Bicarbonate 10mEq/L (24-26), pH 7.2 (7.35-7.45), PCO2 25mmHg (35-45), Alcohol 40mmol/L (0), Osmolality 370mOsm/L (280-295), Glucose 50mg/dl (60-110) BUN 40mg/dl (5-22). What is the acid-base status?

A) Metabolic acidosis

B) Metabolic Alkalosis

C) Respiratory acidosis

D) Respiratory alkalosis

E) Metabolic acidosis with respiratory compensation

Q.5-All of the following statements are correct about potassium balance, except:

A) Most of potassium is intracellular.

B) Three quarter of the total body potassium is found in skeletal muscle.

C) Intracellular potassium is released into extra-cellular space in response to severe injury.

D) Acidosis leads to movement of potassium from extracellular to intracellular fluid compartment.

E) Aldosterone promotes excretion of potassium and reabsorption of sodium.

Q.6- Normal anion gap metabolic acidosis is caused by all except:

A) Cholera

B) Starvation

C) Ethylene glycol poisoning.

D) Lactic acidosis

E) Methanol poisoning.

Q.7- Which of the following is more appropriate for a 17-year-old Female suffering from IDDM with the following blood chemistry report:

pH: 7.2,  PO2 : 108 mm Hg, PCO2 : 12 mmHg and HCO3 : 5 meq/L

A) Metabolic Acidosis with respiratory alkalosis

B) Respiratory Acidosis

C) Metabolic Alkalosis

D) Respiratory alkalosis

E) Metabolic alkalosis with respiratory alkalosis

Q.8- A middle-aged person collapsed on the road side and was brought to emergency, Blood chemistry revealed the following:

pH- 7.51, PCO2– 35 mm Hg, PO2- 62mm Hg and HCO3-27 meq/L.

Which of the following is the most appropriate acid base imbalance in the above said condition?

A) Metabolic acidosis

B) Metabolic alkalosis with respiratory acidosis

C) Respiratory alkalosis with metabolic compensation

D) Respiratory acidosis

E) Metabolic alkalosis with respiratory alkalosis.

Q.9- A 24 –year female reported to the emergency with difficulty in breathing. History revealed that she had ingested some unknown drug. The blood chemistry revealed the following:

PH-7.1; PCO2– 55 mm Hg; PO2-42 mm Hg and HCO317 meq/L

Which of the following is the most appropriate acid base imbalance in the above said condition?

A) Metabolic acidosis with respiratory acidosis

B) Respiratory acidosis

C) Respiratory Alkalosis

D) Metabolic alkalosis

E) None of the above.

Q.10- Which of the following is incorrect about minimum excretory volume?

A) The exact quantity depends on the concentrating power of the kidney

B) The exact quantity depends on the quantity of the solute load

C) The urinary volume is approximately 500 to 600 ml in 24 hrs

D) It is the minimum volume of urine excreted to eliminate the “waste products” of metabolism.

E) It is the amount of urine excreted per day in normal health.

Q.11- The anion gap is calculated as follows: 

A) [K+] + [HCO3– + Cl]

B) [Na+] + [Cl + HCO3]
C) [Na+] – [HCO3– + Cl]

D) [Na+] + [K+]-[Cl- + HCO3]

E) None of the above.

Q.12- ADH release is stimulated by any of the following except:

A) Increased serum osmolality

B) Increased blood volume

C) Decreased Blood pressure

D) Stress

E) Hyponatremia

Q.13- Which of the following is not a cause of pure salt depletion?

A) In mental patients who refuse to drink

B) Excessive sweating

C) Renal failure

D) Mineralocorticoid deficiency

E) Chronic diarrhea

Q.14- Hypokalemia is serum K concentration < 3.5 mEq/L and is caused by:

A) Renal losses

B) GI losses

C) Diuretics

D) Insulin administration

E) All of the above.

Q.15- – Hyponatremia is decrease in serum Na concentration < 136 mEq/L and is caused by :

A) Diuretic use

B) Crush injuries

C) Hemolysis

D) High fever

E) None of the above.

Q.16- Serum sodium concentration is regulated by:

A) Stimulation of thirst,

B) Secretion of ADH,

C) Renin-angiotensin-aldosterone system,

D) Variations in renal handling of filtered sodium

E) All of the above.

Q.17- Factors that shift Potassium in or out of cells include the following:

A) Blood glucose concentration

B) Blood volume

C) Acid-base status

D) Serum Sodium concentration

E) All of the above.

Q.18- Which of the following is not a cause of hyperkalemia?

A) Acute renal failure

B)  Trauma

C) Metabolic acidosis

D) Respiratory alkalosis

E) Intake of bananas.

Q.19- The Henderson-Hassel Balch equation is represented as-

A) pH = pKa + log (A/HA)

B) pH = pKa + log (HA/A)

C) pH = pKa – log(A/HA)

D) pH = pKa – log(HA/A)

E) pH = pKa + log(H+/HA)

Q.20- All are true for renal handling of acids in metabolic alkalosis except

A) Hydrogen ion secretion is decreased

B) Bicarbonate reabsorption is decreased

C) Urinary acidity is decreased

D) Urinary ammonia is decreased

E) Renal Glutaminase activity is increased.

 

Key to answers

1)- D, 2)- D, 3)-B, 4)- E, 5)-D, 6)-A, 7)- A, 8)-E, 9)-A, 10)-E, 11)-C, 12)- B, 13)-A,14)-E, 15)- A, 16)- E, 17)- E, 18)- D, 19)- A, 20)-E.

 

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Q. 1- What is the normal physiological concentration of Hydrogen ion in body fluids?

A) 40 nEq/L

B) 24 mEq/L

C) 400 mEq/L

D) 7.4 nEq/L

E) 100 mEq/L

Q.2- Which of the following is not a source of hydrogen ion in the body?

A) Ingestion of Citrus fruits

B) High protein diet

C) Ingestion of red meat

D) Starvation

E) Chronic alcohol consumption

Q.3- Which of the following is the most important chemical buffer of the plasma?

A) HCO3 /H2 CO3

B) HPO42―/H2PO4

C) Organic Phosphate Esters

D) Proteins

E) Hemoglobin

Q.4- A primigravida in labor is breathing rapidly, what you expect out of the following

A) Metabolic Acidosis

B) Metabolic Alkalosis

C) Respiratory Acidosis

D) Respiratory Alkalosis

E) Any of the above.

Q.5- The Henderson-Hasselbalch equation is represented as-

A) pH = pK + log (A/HA)

B) pH = pK + log (HA/A)

C) pH = pK – log(A/HA)

D) pH = pK – log(HA/A)

E) pH = pK + log(H+/HA)

Q.6- Buffering effect of a buffering solution is optimum at :

A) pH ranges close to pKa± 2 pH units

B) pH = pKa ±3 pH units

C) pH = pKa ±5 pH units

D) pH = pKa

E) None of the above.

Q.7- The pH of extracellular fluid must be maintained between:

A) 6 to 7.4

B) 7 to 7.2

C) 7.35 to 7.45

D) 7.5 to 8

E) 8 to 8.5

Q.8- All are true for renal handling of acids in metabolic acidosis except

A) Hydrogen ion secretion is increased

B) Bicarbonate reabsorption is decreased

C) Urinary acidity is increased

D) Urinary ammonia is increased

E) Renal glutaminase activity is increased

Q.9- Which of the following is most appropriate for a female suffering from Insulin dependent diabetes mellitus with a pH of 7.2, HCO3-17 mmol/L and pCO2-20 mm Hg?

A) High anion gap metabolic Acidosis

B) Metabolic Alkalosis

C) Respiratory Acidosis

D) Respiratory Alkalosis

E) Normal anion gap metabolic acidosis

Q.10-A 50-year-old homeless man was brought to the emergency room in a stuporous state. Below are his lab results, Bicarbonate 10mEq/L (24-26), pH 7.2 (7.35-7.45), PCO2 25mmHg (35-45), Alcohol 40mmol/L (0), Osmolality 370mOsm/L (280-295), Glucose 50mg/dl (60-110) BUN 40mg/dl (5-22). What is the acid-base status?

A) Metabolic acidosis and metabolic alkalosis

B) Metabolic acidosis with partial respiratory compensation

C) Respiratory acidosis and partial metabolic compensation

D) Respiratory acidosis

E) Metabolic alkalosis

Q.11- A 44-year-old man is brought to the emergency room stuporous and obtunded. Serum chemistries are: HCO3 = 42 mEq/L; arterial pH = 7.5; PCO2 = 50mmHg. What is the acid-base status?

A) Metabolic acidosis and metabolic alkalosis

B) Metabolic acidosis with partial respiratory compensation

C) Respiratory acidosis and partial metabolic compensation

D) Respiratory acidosis

E) Metabolic alkalosis

Q.12-The medical student next to you, realizing that there is an examination question on acid base balance, begins nervously hyperventilating and then faints. You make him breathe into a paper bag and he recovers. If you had drawn and analyzed his blood when he fainted you would have expected to see :

A) Decreased pH, decreased pCO2

B) Decreased pH, elevated pCO2

C) Elevated pH, decreased pCO2

D) Elevated pH, elevated pCO2

E) Normal pH, normal pCO2

Q.13- All except one are examples of entoxification:

A) Conversion of methanol to formaldehyde

B) p- methyl amino benzene to p-dimethyl amino azo benzene

C) Conversion of procarcinogens to Ultimate carcinogens

D) Conversion of Aspirin to Acetic acid and Salicylic acid

E) Conversion of Ethyl alcohol to Acetaldehyde.

Q.14- In physiological jaundice of new-born, due to less availability of substrate and immature enzyme system, there is an impaired formation of soluble, non toxic form of bilirubin which is :

A) Bilirubin Sulphate

B) Bilirubin Phosphate

C) Bilirubin diglucuronate

D) Bilirubin Acetate

E) Methylated Bilirubin

15) In  phenylketonuria (a congenital disorder of phenylalanine metabolism that occurs due to deficiency of phenylalanine hydroxylase), there is impaired conversion of phenylalanine to tyrosine. The excess phenylalanine is detoxified and excreted in urine. Which of the following conjugating agents is used for detoxification of phenylalanine?

A) Glutathione

B) Glutamine

C) S-Adenosyl Methionine

D) Active Sulfate (PAPS)

E) D- Glucuronic acid

16) Which of the following is not a cause of secondary dehydration?

A) Excessive sweating

B) Comatose patient

C) Vomiting

D) Diarrhea

E) Congestive heart failure

17) The urinary concentration of sodium chloride (NaCl) ranges between:

A) 2-6 G/litre

B) 4-8 G/litre

C) 5-10 G/litre

D) 6-16 G/litre

E) None of the above

18) The minimum excretory volume to eliminate waste products from the body in dehydration is :

A) 100-200ml

B) 200-400 ml

C) 500-600 ml

D) 1500 ml

E) 600-800 ml

19) Aldosterone acts by promoting:

A) Excretion of Potassium

B) Reabsorption of potassium

C) Reabsorption of sodium

D) Excretion of sodium

E) Reabsorption of sodium and excretion of Potassium

20) Which of the following is not a cause of hypokalemia?

A) Renal tubular acidosis

B) Cushing syndrome

C) GI losses

D) Crush injuries

E) Insulin administration

Key to answers

1)- A, 2)- A, 3)-A, 4)-D, 5)-A, 6)-A, 7)-C, 8)-B, 9)-A, 10)- B, 11)-E, 12)-C, 13)-D, 14)-C, 15)-B, 16)-B, 17)-D, 18)-C, 19)-E, 20)-D.

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Electrolyte Imbalance

Introduction Causes Clinical Manifestations Diagnosis Treatment
Hyponatremia Decrease in serum sodium concentration <136 meq/L caused by excess of water relative to solutes a) Euvolemic Hyponatremia-Polydipsia, Administration of hypotonic fluid, SIADH, Addison’s disease, Hypothyroidism
b) Hypovolemic hyponatremia
i) Renal– Acute or chronic renal  insufficiency, salt wasting nephropathy, use of diuretics,
ii) Extra Renal-vomiting, diarrhea, excessive sweating, prolonged exercise or sodium and water loss but only water is replaced.
c) Hypervolemic Hyponatremia-
i) Renal- Acute or chronic Renal failure nephrotic syndrome
ii) Extra renal- Cirrhosis of liver, Congestive heart failure,
Primarily neurological (Due to osmotic shift of water in to brain cells) and include- Headache, confusion, seizures and coma. 1) Serum and urinary osmolality- serum osmolality may be low but urinary osmolality may be high.2) Serum Sodium –low

3)BUN and creatinine- Normal but high in renal failure.

a) Euvolemia- Treat the primary causeb) Hypovolemia- 0.9% Saline

c) Hypervolemia- fluid restriction and diuretics

Hypernatremia Increase in serum sodium concentration > 145 meq/L caused by a deficit of total body water relative  to total body sodium a) Euvolemic Hypernatremia- i)Renal losses- Central diabetes Insipidus, Nephrogenic diabetes Insipidusii) Extra renal losses- Respiratory tract (Tachypnea). Skin (Fever)

iii) Misc- Decreased thirst

b) Hypovolemic Hypernatremia-

i) GI Losses- Diarrhea, vomiting

ii) Skin- Burns, excessive sweating

iii) Renal losses-Interstitial kidney disease, diuretics etc.

c) Hypervolemic hypernatremia- Administration of hypertonic fluid, saline or sodium bicarbonate, excess mineralocorticoids

 

Thirst, CNS Dysfunction, confusion, seizures or coma, decreased skin turgor in severe cases 1) Serum sodium high2) BUN , creatinine high- if kidneys are involved

3) Urinary sodium- > 20 meq/L in Hypovolemic hypernatremia and

< 20 meq/L  if there are extra renal losses.

 

a) Euvolemic Hypernatremia- 5% D/W or 0.45% salineb) Hypovolemic Hypernatremia-

0.45% saline or a combination of 0.9% normal saline and 5% D/W

c) Hypervolemic hypernatremia-

5% D/W with loop diuretics

d) Sodium restricted diet

Hypokalemia Serum K concentration < 3.5 meq/L, caused by deficit in total body K or shift of potassium in to the cells i) Renal Losses- Renal tubular acidosisii) Adrenal steroid excess- Cushing syndrome, Hyperaldosteronism

iii) GI Losses- Vomiting, diarrhea, laxative abuse

iv) Drug induced- Diuretics, Beta 2 adrenergic agonists, steroids, theophyllin, insulin administration

v) Metabolic alkalosis

vi) Familial periodic paralysis

Fatigue, Myalgias, weakness, hypoventilation, impaired muscle metabolism, glucose intolerance 1)Serum potassium is lowa) ECG- Findings-Sagging of ST segment. T wave depression, elevation of U wave.

AV blocks  or Arrhythmias in severe cases

3) BUN and Creatinine may be high, serum calcium high, Ph High. Blood glucose may be high

Supplementation by oral route or I/V KCl mixed in normal saline.
Hyperkalemia Serum K concentration > 5.5 meq/L from excess total body potassium stores or abnormal movement of K out of the cells a)Pseudohyperkalemia– Hemolysis, Thrombocytosis, Leukocytosisb) Redistribution- Acidosis, Insulin deficiency, beta blocker drugs, digitoxin overdosage, hyperkalemic periodic paralysis

c) Excessive endogenous load- Hemolysis, Rhabdomyolysis, Internal hemorrhage

d) Excessive exogenous load- Parenteral administration, excess in diet, K supplements.

e) Diminished excretion- Renal failure, renal tubular acidosis

 

Fatigue, Paresthesias, paralysis, palpitations, bradycardia, decreased tendon reflexes, decreased motor strength.Signs of renal failure or muscle paralysis may be there. 1) Serum K is low2) ECG- Increased PR interval, Tall , symmetric , peaked T waves.

In severe cases- widening of QRS interval, ventricular arrhythmias, ventricular fibrillation

3) BUN, Creatinine may be high

4) Blood glucose high in diabetes mellitus

5) PH low in acidosis

1) Supplement with calcium chloride or calcium GluconateTo restore resting membrane potential

2) Insulin with glucose supplementation to promote intracellular shift.

 

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