Mineral Disorders - 4th Year Medicine

Mineral Disorders - 4th Year Medicine

• Learning Outcomes: Students will be able to define normal and abnormal plasma magnesium, sodium, potassium, and calcium levels; identify disorders associated with abnormal mineral levels; and describe laboratory tools for mineral concentration estimation.

Magnesium (Mg)

• Abundance: Magnesium is the fourth most abundant cation (Mg²⁺) in the body.
• Total Body Content: Total body content is 21-28 g.
• Normal Serum Levels: Normal serum levels are 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) Function

• Muscles and Nerves: Crucial for proper muscle and nerve function.
• ATP Complexation: Forms a complex with ATP, acting as a cofactor for various enzymes in metabolism, replication, and transport.
• Metabolism Regulation: Essential for sodium, potassium, calcium, vitamin C, and phosphorus metabolism.
• Electrolyte Balance: Maintains electrolyte balance.
• Anti-Stress: Possesses anti-stress properties.

Hypomagnesemia

• Definition: Clinically significant deficiency of less than 1.2 mg/dL.
• Renal Causes: Hypercalcemia, tubular disorders in the kidney, hyperaldosteronism, and diuretics.
• Extrarenal Causes: Malnutrition, malabsorption (chronic diarrhea or laxative abuse), increased cell uptake of magnesium, and increased bone storage after parathyroidectomy.

Hypermagnesemia

• Rarity: Rare, mostly in patients with renal failure using magnesium-containing drugs.

Blood Sodium

• Plasma Levels: Plasma levels range from 132 to 144 mmol/L.
• Daily Requirements: Daily requirements are 5 to 15 g in the form of NaCl.
• Excretion: About 95% of sodium exiting the body is excreted in urine.

Sodium Distribution and Functions

• Distribution: One-third of total body sodium is found in the skeleton, while the majority is found in extracellular fluids.
• Acid-Base Balance: Associated with chloride and bicarbonate for regulating acid-base balance.
• Fluid Balance: Important for maintaining body fluids and protecting against excessive fluid loss.
• Muscle and Cell Function: Crucial for normal muscle irritability and cell permeability.

Hypernatremia Causes

• Sodium Salt Administration: Rapid sodium salt administration.
• Adrenal Cortex Hyperactivity: Cushing's disease.
• Corticotrophin Administration: Corticotrophin (ACTH) and cortisone administration.
• Dehydration: Dehydration, as seen in diabetes insipidus.

Hyponatremia Causes

• Adrenocortical Insufficiency: Adrenocortical insufficiency due to sodium loss.
• Chronic Renal Failure: Cases of chronic renal failure.
• Liver Cirrhosis: Liver cirrhosis.
• Congestive Heart Failure: Congestive heart failure.
• Gastrointestinal Fluid Loss: Excessive loss of gastrointestinal fluids (severe diarrhea).
• Excessive Sweating: Excessive sweating.

Blood Potassium

• Plasma Levels: Normal levels in plasma range from 3.6 to 4.8 mmol/L.
• Distribution and Function: The principle intracellular cation, yet also crucial for extracellular fluid. Influences muscle activity, especially in cardiac muscles. Plays a role in acid-base balance.
• Metabolic Function: Essential for metabolic functions like protein synthesis, glycogenesis, and glycogenolysis.

Hyperkalemia Causes

• Renal Failure: Renal failure.
• Dehydration: Dehydration.
• Adrenal Insufficiency: Adrenal insufficiency (Addison's disease).

Hyperkalemia Symptoms

• Nervous system and cardiac symptoms: Central nervous system symptoms and cardiac symptoms in the form of bradycardia and poor heart sounds occurring.
• Peripheral circulatory collapse and cardiac arrest: Peripheral vascular collapse and cardiac arrest may follow.
• Other Symptoms: Mental confusion, numbness, weakness in respiratory muscles, and paralysis in extremities.

Hypokalemia Causes

• Chronic Diseases and Malnutrition: Chronic diseases with malnutrition.
• Gastrointestinal Losses: Gastrointestinal losses (vomiting, diarrhea).
• Adrenal Cortex Overactivity: Overactivity of the adrenal cortex (Cushing's syndrome).
• Diuretic use: Use of diuretics like acetazolamide and chlorothiazide.

Hypokalemia Symptoms

• Muscle weakness, irritability, and paralysis: Muscle weakness, irritability, and paralysis are key symptoms.
• Tachycardia: Tachycardia also accompanies hypokalemia.

Blood Calcium

• Distribution: Predominantly stored in bone and teeth (99%).
• Intracellular Calcium: 1% of calcium in intracellular locations, mainly mitochondria and endoplasmic reticulum.
• Extracellular Calcium: 0.1% of calcium in extracellular fluid (plasma calcium levels 9-11 mg/dL).

Calcium Function

• Bone and Teeth: Main mineral component of bone and teeth.
• Nerve Impulse Transmission: Essential for nerve impulse transmission.
• Muscle Contraction: Important in muscle contraction.
• Enzyme Activation: Required for activating specific enzymes.
• Blood Clotting: Crucial for blood clotting.

Hypocalcemia Causes

• Hypoparathyroidism: Low levels of parathyroid hormone.
• Vitamin D Deficiency: Vitamin D deficiency.
• Low Serum Albumin: Low serum albumin levels.
• Hypomagnesemia: Hypomagnesemia.
• Medullary Thyroid Carcinoma: Medullary thyroid carcinoma.
• Chronic Renal Insufficiency: Chronic renal insufficiency.
• Malabsorption: Problems with nutrient absorption.
• Alcoholism: Alcoholism.

Hypercalcemia Causes

• Primary Hyperparathyroidism: Primary hyperparathyroidism.
• Secondary Hyperparathyroidism: Secondary hyperparathyroidism (in renal failure).
• Vitamin D Toxicity: Vitamin D toxicity.
• Tumors Producing PTH-related Proteins: Tumors producing PTH-related proteins.
• Bone Metastasis: Bone metastasis.

Laboratory Tools - Mineral Levels

• Spectrophotometer: Measures the amount of light absorbed by a sample, crucial for determining mineral concentrations.
• Routine Automated Biochemistry Analyzers: Automated machines processing large volumes of samples, reducing errors and time for analysis.
• Blood Tests: Tests using blood samples to measure amounts of minerals.
• Red Blood Cell Tests: “Gold standard” for detecting mineral deficiencies.
• Urine Tests: Quantitative analysis of minerals in urine samples. Tests can determine mineral deficiency or toxicity.

Calculation of Concentration Using Absorbance

• Formula: Concentration (C_test) = (Absorbance (A_test) / Absorbance (A_standard)) × Concentration (C_standard)

Procedure for Spectrophotometer Use

1. Warm-up: Warm up the instrument for 15 minutes.
2. Set Wavelength: Set the wavelength appropriate for the sample.
3. Wipe Cuvette: Wipe the reference solution cuvette with tissue paper.
4. Place Cuvette: Place the reference solution cuvette into the sample holder. Close the cover.
5. Zero Absorbance: Set absorbance to zero.
6. Replace With Standard/Sample: Remove the reference cuvette, and add standard (check its cuvette). Add sample cuvette (check its cuvette).
7. Read Absorbance: Read and record the absorbance.
8. Calculate Concentration: Calculate the sample concentration using the formula.

This quiz focuses on the understanding of mineral disorders affecting magnesium, sodium, potassium, and calcium levels in the body. Participants will learn about normal versus abnormal plasma levels, related disorders, and the laboratory tools used for mineral concentration estimation. Perfect for 4th year medical students looking to solidify their knowledge in this essential area.