Ep05: Acid-Base Balance
The last 5 sections have focused on electrolytes and a calculation called the anion gap. In this section, I want to focus in a bit and put all of that information together by looking at the role of Functional Blood Chemistry Analysis in uncovering imbalances in the body’s acid-base system.
The following are some of the Acid-Base abnormalities that can be assessed using Blood chemistry and CBC analysis.
- Metabolic alkalosis
- Metabolic acidosis
But before we dive into these I want to revisit CO2 and Chloride, 2 biomarkers I covered a few weeks ago and look at them through the perspective of acid-base or pH balance.
CO2 and Acid-Base Balance
Serum CO2, as bicarbonate, is one of the reserve alkaline elements in the blood and is the form of CO2 measured on a blood test.
Bicarbonate, as that reserve alkali, neutralizes metabolic acids, such as hydrochloric and lactic acids.
While not the most sensitive measurement of pH, serum CO2 is something that can be measured on a simple chemistry screen so we can use it to help evaluate for a trend towards metabolic acidosis or alkalosis.
Elevated levels of serum CO2, or bicarbonate, are associated with a trend towards Metabolic Alkalosis and decreased levels are associated with a trend towards Metabolic Acidosis
Chloride and Acid-Base Balance
Chloride, along with sodium, potassium, and C02, plays a role in maintaining acid-base.
Chloride has an inverse relationship with CO2 levels
- Metabolic acidosis will have an increased chloride level and a decreased CO2 level.
- Metabolic alkalosis will have decreased chloride and an increased CO2.
Chloride ions are excreted along with other cations, such as sodium, potassium, during diuresis and are lost from the stomach during bouts of vomiting and/or diarrhea, which can have serious implications for acid-base balance.
Now that we have that out the way let’s take a look at our first acid-base abnormality: Metabolic alkalosis
In metabolic alkalosis, there are increasing levels of bicarbonate ion in relation to H+.
Some of the causes of a bicarbonate increase include:
- All diuretic therapies (cause loss of fluid and excess excretion of H+ as sodium gets rapidly resorbed)
- Excess vomiting (loss of H+)
- Excess secretion of aldosterone (loss of potassium from urine causes sodium and H+ to move into the cell thus decreasing serum levels. H+ is also excreted in urine with potassium, leaving a net loss of H+)
- Excess ingestion of alkaline drugs e.g. H2 blockers
- Excess consumption of bicarbonate e.g. antacids
Metabolic Alkalosis Signs and Symptoms
- Alkaline urine
- Water and fluid retention
- Poor digestion- hypochlorhydria
- Joint and muscle pain
- Leg and muscle cramps, tetany
- Urinary calculi (kidney stones)
- Cold, clammy hands and feet
- Excitability of nervous system
- Low blood pressure
Metabolic Alkalosis – FBCA Pattern
Given all that, what shifts in a blood chemistry screen will alert us to a developing Metabolic Alkalosis?
- First off, the Serum CO2 which if you remember represents the buffer bicarbonate will be increased.
- Chloride will go the other way and will be decreased.
- Potassium levels may or may not be decreased and you will likely see a decrease in the serum calcium level as well. If you see all 4 of these then there is likely a trend towards metabolic alkalosis.
Further in-office lab testing (breath-hold time, respiration rate, salivary and urine pH studies) may be necessary to further elucidate this pattern. I cover these in my In-Office Lab Testing book along with a more in-depth discussion on pH balance!
Now, let’s switch gears to talk about what is probably more common to see and that’s a Metabolic Acidosis.
In metabolic acidosis, the body is in a state of increasing levels of H+ ion.
Some of the causes of an H+ increase include:
- Inefficient formation of ATP
- Incomplete digestion/ oxidation of macronutrients
- Direct administration or production of acid – dietary acids such as soda (high levels of phosphoric acid), coffee, alcoholor aspirin use (salicylic acid).
- Loss of bicarbonate: acute and chronic diarrhea
- Increasing kidney stress (fail to process H+)
- Anaerobic respiration or lack of exercise
- Increased stressLiver dysfunction
Metabolic Acidosis Signs and Symptoms
- Acid urine
- Excess fluid excretion and dehydration
- Poor digestion
- Hyperactivity and insomnia
- Poor retention of minerals
- High blood pressure and rapid heart rate
- Warm, dry hands and feet
- Dry mouth
Metabolic Acidosis- FBCA Pattern
Given all that, what shifts in a blood chemistry screen will alert us to a developing Metabolic Acidosis?
- The serum CO2 will be decreased in metabolic acidosis (the bicarbonate is being used-up to buffer the increasing levels of H+ in the body).
- Chloride levels will be increased
- The anion Gap will be increased
- Potassium levels may be increased because metabolic acidosis drives potassium from the cell and it causes an increased level to be in the serum.
As with Metabolic Alkalosis, further in-office lab testing (breath-hold time, respiration rate, salivary and urine pH studies) may be necessary to further elucidate this pattern.