Hyponatremia and hypobicarbonatemia

Question

What is the answer to the following question? And why?

An untreated patient with which one of the following conditions is MOST LIKELY to present with (relative to a healthy individual) decreased plasma bicarbonate and decreased total body sodium?

• (a) diabetic ketoacidosis
• (b) carbon monoxide poisoning
• (c) anaphylactic shock
• (d) severe iron-deficiency anaemia
• (e) a panic attack and hyperventilation

Answer 1

Carbonic Acid / Bicarbonate Buffer System

CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3

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Metabolic Acidosis and DKA

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Includes the following:

• Decreased pH

• Low HCO3 levels

• This condition occurs when acids other than carbonic acid accumulate in ECF or when there is a loss of HCO3.

• Rarely occurs spontaneously but in is with other problems (starvation, shock, trauma... but the answer you're looking for is.......

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ANSWER

Diabetic Ketoacidosis (DKA)

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Key Points (Information Below MerekManual Professional Version)

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• Metabolic acidosis can be caused by acid accumulation due to increased acid production or acid ingestion; decreased acid excretion; or GI or renal HCO3− loss.
• Metabolic acidoses are categorized based on whether the anion gap is high or normal.
• High anion gap acidoses are most often due to ketoacidosis, lactic acidosis, renal failure, or certain toxic ingestions
• Normal anion gap acidoses are most often due to GI or renal HCO3− loss
• Calculate delta gap to identify concomitant metabolic alkalosis, and apply Winters formula to see whether respiratory compensation is appropriate or reflects a 2nd acid-base disorder.
• Treat the underlying cause
• NaHCO3 is indicated when acidosis is due to a change in HCO3− (normal anion gap acidosis)
• Intravenous NaHCO3 is controversial in high anion gap acidosis (but may be considered when pH < 7.00, with a target pH of ≤ 7.10).

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Sources:

http://www.webmd.com/diabetes/tc/diabetic-ketoacidosis-dka-topic-overview#1

http://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/acid-base-regulation-and-disorders/metabolic-acidosis