Micronutrients and Common Vitamin & Mineral Deficiencies

Micronutrients include what?

vitamins, minerals, and trace elements

What is the range for micronutrients?

mg-ug

What do micronutrients primarily function as?

• cofactors/coenzymes

• structural components

• regulator molecules

Micronutrient deficiencies often present [ ] before overt [ ] occurs

subtly, disease

Micronutrient insufficiencies often increase the risk of…?

other conditions/diseases

What are the high risk populations for mineral deficiencies?

1. Elderly

2. surgical patients (e.g. gastric bypass)

3. alcohol use disorder, substance use disorder

4. malabsorption syndromes

What do fat soluble vitamins require for absorption?

bile salts and intact small intestine

How are water soluble vitamins absorbed?

via transporters in proximal intestine

What is a often a requirement for the transport of micronutrients?

carrier proteins

What are examples of micronutrient carrier proteins?

• vitamin D- vitamin D binding protein

• iron- transferrin

• vitamin B12- transcobalamin 2

How are water soluble vitamins usually stored?

minimal storage except for B12

Describe the storage of fat-soluble vitamins?

large hepatic and adipose stores

Toxicity Risk of fat-soluble vitamins? And example

accumulate and have higher risk of toxicity

• ex: excessive vitamin A leads to intracranial hypertension, tetratogenicity

Toxicity risk of water soluble vitamins?

usually excreted, minimal risk

What are absorption mechanisms/key features for fat-soluble vitamins?

• chylomicrons into lymphatics

• stored in liver and adipose tissue

• slow turnover

What are the fat-soluble vitamins?

Vitamin A, D, E, and K

What is vitamin A also known as?

retinoids

What is are the major functions of vitamin A?

• vision: retinal → rhodopsin

• cell differentiation →epithelial integrity, immune function

What are vitamin A deficiency symptoms?

• night blindness (early)

• xerophthalmia, bitot spots

• keratinization

What are examples of vitamin A toxicities?

• teratogenic (pregnancy complications)

• hepatotoxicity

• pseudotumor cerebri

What are the two major functions of vitamin D?

1. increases intestinal calcium and phosphate absorption

2. bone mineralization

What are different forms of vitamin D?

• Vitamin D2

  • found in food, intestines

• Vitamin D3

  • synthesized by skin and converted to D2 in intestine

• 25[OH]D3 (25 hydroxycholecalciferol)

  • converted from cholecalciferol in liver

• 1,25[OH]D3 (1,25-dihydroxycholecalciferol

  • converted form 25[OH]D3 in kidney by 1-alpha-hydroxylase

How is vitamin D regulated?

UV through skin → liver (25-OH) → kidney (1,25 OH) *here it is under control of parathyroid hormone (PTH)*

Common Vitamin D deficiency leads to what?

• rickets

  • children, bowed legs

• osteomalacia

  • adults, bone pain

What are chronic signs of low vitamin D?

low calcium, high parathyroid hormone, high alkaline phosphatase (ALP)

How is vitamin D related to chronic kidney disease?

CKD recues synthesis of 1,25 OH, and causes secondary hyperparathyroidism

What is the major function of vitamin E?

antioxidant (protects cell membranes)

What does vitamin E deficiency lead to?

• hemolytic anemia (RBC oxidative damage)

• neurologic symptoms

  • ataxia and peripheral neuropathy

What are the clinical relationships for vitamin E?

• fat malabsorption syndromes

• mimics B12 neurologic findings

What is the major function of vitamin K?

gamma-carboxylation of clotting factors: II, VII, IX, X + protein C/S

What forms can vitamin K be found in?

1. circulating: phylloquinone (vitamin K1)

2. stored in liver: menaquinone (vitamin K2)

3. produced by gut microflora

What are results of vitamin K deficiency?

• increased prothrombin time (early)

• bleeding tendencies

How do dicoumarin drugs relate to vitamin K?

They interfere with vitamin K’s role in blood clots, to treat deep vein thrombosis, pulmonary emboli, or to prevent thrombus in patients with atrial fibrillation

What does the warfarin mechanism do?

inhibits vitamin K-dependent carboxylation of clotting factors

Why do newborns get vitamin K injections?

Since they have a sterile gut, they need to get injections

what do broad spectrum antibiotics do to vitamin K levels?

Can cause vitamin K deficiency by reducing gut flora

If there is mention of carboxylation regarding micronutrients, what vitamin is it most likely pertaining to?

vitamin K

What are the core principles regarding water-soluble vitamins?

minimal storage, more likely for deficiency to occur

excess is excreted in urine

What are the clinical patterns of water-soluble deficiencies (rapid and chronic)?

Rapid deficiencies: Thiamin (B1), folate (B9)

chronic deficiencies: vitamin B12

What are the main water soluble vitamins?

thiamine, niacin, folate, vitamin B12, vitamin C

What are the main functions of thiamine?

1. central to energy metabolism

2. cofactor for pyruvate dehydrogenase, a-ketoglutarate dehydrogenase, and transketolase

3. active form: thiamine pyrophosphate (TPP)

What are examples of thiamine deficiencies?

• beriberi

• wernicke encephalopathy

• korsakoff syndrome

what can cause beriberi?

alcohol use disorder

What are symptoms of Wernicke encephalopathy?

confusion, ophthalmoplegia, and ataxia

What are symptoms of korsakoff syndrome?

memory loss, confabulation

What are the major functions of niacin?

1. central to energy metabolism

2. cofactor for oxidoreductase reactions (NAD+ and NADP+ reactions)

What is the main niacin deficiency?

Pellagra

What are the 3Ds of pellagra?

dermatitis, diarrhea, and dementia (4th is death)

When does pellagra occur?

In Hartnup disease due to tryptophan (precursor to niacin) deficiency

Nicotinic acid is used to lower what?

cholesterol levels

What is the shared function of folate and vitamin B12?

DNA synthesis

What are the differences between folate an vitamin B12?

Folate: no neurologic symptoms, is caused by poor diet, and will have normal methylmalonic acid (MMA) levels

Vitamin B12: neurologic symptoms are present, occurs in malabsorption and pernicious anemia, elevated MMA levels

If someone has megaloblastic anemia, what deficiency could they have?

vitamin B12 or folate

What does pernicious anemia indicate?

that someone has a vitamin B12 deficiency

How is vitamin B12 absorbed?

binds with intrinsic factor in small intestines and is absorbed in the ileum

If the intrinsic factor for vitamin B12 is lost, what can occur?

gastric atrophy, loss of parietal cells, gastric bypass

or

reduced absorption- ileum resection, chron disease

What are the major functions of vitamin C?

• collagen synthesis (hydroxylation)

• antioxidant

• enhances iron absorption and carrying (Fe2+ vs Fe3+)

What is scurvy?

vitamin C deficiency

What do bleeding gums, petechiae, and poor wound healing indicate?

vitamin C deficiency, specifically scurvy

Describe vitamin C toxicity?

rare, oxalate renal stones

What is vitamin B2?

riboflavin

what is vitamin B5?

pantothenic acid

What is vitamin B6?

pyridoxine

What is pyridoxine?

It is involved in multiple metabolic pathways, is required for synthesis of some neurotransmitters

What happens during pyridoxine deficiency?

neuropathy, seizures, sideroblastic anemia (iron granules)

What is vitamin B7?

biotin

What can consumption of raw eggs cause?

biotin deficiency by blocking absorption

What are the two categories of minerals?

Major and trace

What are major minerals?

calcium, phosphorous, magnesium

What are trace minerals?

iron, zinc, iodine, selenium

What are the functions of minerals?

1. structural (bone)

2. enzyme cofactors

3. hormonal synthesis

What are the functions of calcium and phosphate?

• bone structure

• cellular signaling

• ATP

What regulates calcium and phosphate and how?

parathyroid hormone (increases calcium, decreases phosphate)

vitamin D (increase calcium and phosphate)

What is a sign of hypocalcemia?

tetany, seizures

What are signs of hypercalcemia?

“stones, bones, groans”

What are the functions of iron?

• oxygen transport (hemoglobin, myoglobin)

• electron transport

Where is iron absorbed?

duodenum

How does iron impact vitamin c?

enhances vitamin C absorption

What regulates iron absorption?

hepcidin

What does microcytic anemia, fatigue and pallor indicate?

iron deficiency

How do you test for iron deficiency?

ferritin

• low ferritin = iron deficiency

Describe function of zinc?

enzyme function, wound healing

Function of Iodine

thyroid hormone synthesis

What does hypothyroidism and goiter indicate?

iodine deficiency

What is the function of selenium?

antioxidant (glutathione peroxidase)

What does cardiomyopathy, specifically Keshan disease, indicate?

selenium deficiency

Potassium is involved with what in the body?

membrane potential, acid-base balance

Hypokalemia, muscle cramps, and irregular heart rhythms indicate what?

potassium deficiency

What mineral promotes blood volume homeostasis, and is involved with the membrane potential?

sodium

Hyponatremia, vomiting, seizures, and cramps indicate what?

sodium deficiency

What is chloride doing in the body?

nerve conduction, stomach acid

What is the common supplement to prevent muscle weakness, fatigue, and irregular heart beats?

Magnesium

If hydroxylation is mentioned, what micronutrient is it related to?

Vitamin C