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Questions and Answers
What are the four minerals discussed in this lecture?
What are the four minerals discussed in this lecture?
The majority of magnesium in the body is stored in muscles and soft tissues.
The majority of magnesium in the body is stored in muscles and soft tissues.
False
What is the normal range of serum magnesium in mg/dL?
What is the normal range of serum magnesium in mg/dL?
What is the main function of magnesium in relation to ATP?
What is the main function of magnesium in relation to ATP?
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What are the two primary causes of hypomagnesemia?
What are the two primary causes of hypomagnesemia?
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What is the normal range of plasma sodium in mmol/L?
What is the normal range of plasma sodium in mmol/L?
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The majority of sodium in the body is found in intracellular fluids.
The majority of sodium in the body is found in intracellular fluids.
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What are the two main functions of sodium in the body?
What are the two main functions of sodium in the body?
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What is the most common cause of hypernatremia?
What is the most common cause of hypernatremia?
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Potassium is an essential element in both intracellular fluid and extracellular fluid.
Potassium is an essential element in both intracellular fluid and extracellular fluid.
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What is the normal amount of potassium in plasma, in mmol/L?
What is the normal amount of potassium in plasma, in mmol/L?
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Which of the following is NOT a cause of hyperkalemia?
Which of the following is NOT a cause of hyperkalemia?
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Hypokalemia mainly affects the central nervous system.
Hypokalemia mainly affects the central nervous system.
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Where is the majority of calcium stored in the body?
Where is the majority of calcium stored in the body?
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Calcium is required for blood clotting.
Calcium is required for blood clotting.
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What are the two main causes of hypocalcemia?
What are the two main causes of hypocalcemia?
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Hypercalcemia is a common condition.
Hypercalcemia is a common condition.
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What is the purpose of a spectrophotometer in laboratory testing?
What is the purpose of a spectrophotometer in laboratory testing?
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What is the first step in using a spectrophotometer?
What is the first step in using a spectrophotometer?
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The concentration of a substance is directly proportional to the amount of light absorbed.
The concentration of a substance is directly proportional to the amount of light absorbed.
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Which of the following is NOT a step involved in using a spectrophotometer?
Which of the following is NOT a step involved in using a spectrophotometer?
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What is the formula used to calculate the concentration of a sample using a spectrophotometer?
What is the formula used to calculate the concentration of a sample using a spectrophotometer?
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Automated biochemistry analyzers can process a large portion of samples going into a hospital laboratory.
Automated biochemistry analyzers can process a large portion of samples going into a hospital laboratory.
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What are two advantages of using automated biochemistry analyzers?
What are two advantages of using automated biochemistry analyzers?
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What is the gold standard for evaluating mineral deficiency?
What is the gold standard for evaluating mineral deficiency?
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What type of analysis is performed for urine samples?
What type of analysis is performed for urine samples?
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A urine test can help determine if a person has mineral toxicity.
A urine test can help determine if a person has mineral toxicity.
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Study Notes
Mineral Disorders - Overview
- Course: 4th Year Medicine, Laboratory Medicine Course
- Instructor: Jehad Tayyeb, Clinical Biochemistry Department
- Year: 2023
Intended Learning Outcomes
- Students will understand normal and abnormal levels of plasma magnesium, sodium, potassium, and calcium.
- Students will be able to explain disorders associated with abnormal mineral levels.
- Students will learn about common laboratory tools for estimating mineral concentrations.
Magnesium (Mg)
- Fourth most abundant cation (Mg2+) in the body.
- Total body content: 21-28 g
- Normal serum Mg: 1.7-2.5 mg/dL
- Distribution:
- 53% stored in bone
- 46% in muscles and soft tissues
- 1% extracellularly in blood and RBCs
Magnesium (Mg) Functions
- Crucial for muscle and nerve function
- Forms a complex with ATP, acting as a cofactor for various enzymes, transporters, and nucleic acids
- Required for normal cellular function, replication, and energy metabolism
- Important for the metabolism of sodium, potassium, calcium, vitamin C, and phosphorus
- Maintains electrolyte balance
- Has anti-stress properties
Hypomagnesemia
- Clinically significant deficiency: <1.2 mg/dL
- Renal causes:
- Hypercalcemia
- Tubular disorders in the kidney
- Hyperaldosteronism
- Diuretics
- Extrarenal causes:
- Malnutrition
- Malabsorption, chronic diarrhea, or laxative abuse
- Increased cell uptake of Mg
- Increased storage in bone seen after parathyroidectomy
Hypermagnesemia
- Rare, primarily in patients with renal failure using Mg-containing drugs.
Blood Sodium
- Plasma level: 132-144 mmol/L
- Daily requirements: 5-15 g in the form of NaCl
- Excretion: About 95% of sodium is excreted in urine.
Sodium Distribution and Functions
- About one-third of total body sodium is in the skeleton.
- Most sodium is found in extracellular fluids.
- Associated with chloride and bicarbonate for acid-base balance regulation.
- Essential for maintaining body fluids and protecting against excess fluid loss.
- Influences normal muscle irritability and cell permeability.
Causes of Hypernatremia
- Rapid administration of sodium salt
- Hyperactivity of adrenal cortex (Cushing's disease)
- Administration of corticotrophin (ACTH), cortisone
- Dehydration (e.g., diabetes insipidus)
Causes of Hyponatremia
- Adrenocortical insufficiency (increased sodium loss)
- Chronic renal failure
- Liver cirrhosis
- Congestive heart failure
- Excess loss of gastrointestinal fluids (severe diarrhea)
- Excess sweating
Blood Potassium
- Red blood cells contain significant potassium.
- Normal plasma potassium: 3.6-4.8 mmol/L
- Principal intracellular cation but also important in extracellular fluid for influencing muscle activity, especially cardiac muscles.
- Essential for regulating acid-base balance.
- Required for protein synthesis, glycogenesis, and glycogenolysis.
Causes of Hyperkalemia
- Renal failure
- Dehydration
- Adrenal insufficiency (Addison's disease)
- Symptoms include central nervous system symptoms and cardiac issues (bradycardia, poor heart sounds, vascular collapse, cardiac arrest). Other symptoms include mental confusion, numbness, weakness of respiratory muscles, and paralysis.
Causes of Hypokalemia
- Chronic diseases with malnutrition
- Gastrointestinal losses (vomiting, diarrhea)
- Overactive adrenal cortex (Cushing's syndrome)
- Use of diuretics (e.g., acetazolamide, chlorothiazide)
- Symptoms include muscle weakness, irritability, paralysis, and tachycardia
Calcium Distribution
- 99% of body calcium is stored in bone and teeth.
- 1% is intracellular (mainly in mitochondria and endoplasmic reticulum).
- 0.1% is extracellular (plasma calcium 9-11 mg/dL).
Calcium Functions
- Major mineral in bone and teeth
- Essential for nerve impulse transmission
- Important in muscle contraction
- Required for enzyme activation
- Crucial for blood clotting
Hypocalcemia
- Decrease in plasma calcium level below 9 mg/dL
- Causes:
- Hypoparathyroidism
- Vitamin D deficiency
- Low serum albumin
- Hypomagnesemia
- Medullary carcinoma of the thyroid
- Chronic renal insufficiency
- Malabsorption
- Alcoholism
Hypercalcemia
- Increase in plasma calcium level above 11 mg/dL
- Causes:
- Primary hyperparathyroidism
- Secondary hyperparathyroidism (e.g., in renal failure)
- Vitamin D toxicity
- Tumors producing PTH-related proteins
- Bone metastasis
Laboratory Tools for Mineral Levels
- Spectrophotometer.
- Routine Automated Biochemistry Analyzers
- Blood test (needle to draw blood from veins)
- Urine test (quantitative analysis of urine samples)
- Red blood cell test ("gold standard" for evaluating mineral deficiency
Spectrophotometer Operation Steps
- Warm-up (15 min)
- Set wavelength
- Wipe cuvette with reference solution
- Place cuvette into sample holder, close cover
- Set absorbance to zero
- Remove reference tube, add standard and sample tubes
- Read and record absorbance
- Calculate sample concentration
Concentration Calculation Formula:
- Ctest = (Atest / Astandard) x Cstandard
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Description
This quiz focuses on the overview of mineral disorders, particularly magnesium, sodium, potassium, and calcium levels. Students will explore the normal and abnormal levels, associated disorders, and laboratory tools used for estimation. It's essential for understanding clinical biochemistry in the context of laboratory medicine.
