Vitamin deficiencies Flashcards
1
Q
What is the primary disease caused by vitamin A deficiency?
A
Xerophthalmia
Describes a spectrum of ocular manifestations that occur secondarily to systemic vitamin A (retinol) deficiency
2
Q
Describe the aetiology of xerophthalmia
A
Vitamin A (retinol) is required for formation of rhodopsin, photoreceptor pigment in the retina.
Keratinisation of the eyes → dryness of the conjunctiva and cornea
- Conjunctivae develop oval/triangular spots (Bitots spots)
- Cornea becomes cloudy and soft.
3
Q
State some causes of vitmain A deficiency
A
- Conditions that affect pancreatic function, such as:
- cystic fibrosis
- chronic pancreatitis
- Conditions that lead to reduced absorption of vitamin A, such as:
- previous gastric surgery
- Crohn’s disease
-
Liver conditions:
- Liver stores vitamin A
-
Inadequate intake:
- Common in southern and eastern Asia where rice is the staple food
- rice is devoid of beta carotene (precursor to vit A)
4
Q
What are the presenting symptoms of vitamin A deficiency?
A
- First symptom = night blindness
- multiple erosions develop = eventual blindness
- Drying, scaling and follicular thickening of the skin due to keratinisation
- Respiratory infections due to keratinisation of mucous membranes in respiratory tract.
5
Q
Recognise the signs of vitamin A deficiency
A
Visual ability
-
decreased visual acuity in dim light
- measure using Snellen chart
- visual field loss
On Fundoscopy:
-
Retinal vascular attenuation
- narrowing of the retinal arterioles.
- Bitots spots on conjunctiva
- peripheral chorioretinal degeneration
On observation
- corneal xerosis – cornea appears dry and dull
- corneal ulcerations
- Conjunctival xerosis – dry, dull and thick
6
Q
What is the final stage of xerophthalmia before blindness?
A
Keratomalacia
softening of cornea, followed by perforation of eyeball and blindness
7
Q
State appropriate investigations for Vit A deficiency
A
Check sight in darkness
Bloods:
- Serum vitamin A level
- Serum retinol binding protein
- Zinc levels – zinc deficiency can interfere with production of retinol-binding protein
- Iron studies – can affect metabolism of vitamin A
- FBC: for anaemia or infection
8
Q
Identify the possible complications of vitamin A deficiency
A
- Blindness
- Respiratory infections
- Prognosis good if treated early, before blindness progresses
9
Q
Vitamin B1 (thiamine)deficiency precipitates which disease?
A
Beri Beri
Can progress to Wernicke’s encephalopathy
10
Q
Explain the risk factors for vitamin B1 deficiency
A
Developed world:
- Chronic alcohol abuse- commonest
-
Refeeding and TPN
- B1 = co-factor in the metabolism of carbohydrates
- GI surgery, including bariatric surgery, can lead to a reduced area of intestinal and gastric mucosa for absorbing thiamine
-
Cancer and chemotherapy
- N+V, anorexia, malabsorption
Developing world:
-
High levels of milled (polished) rice
- polished rice is deficient in thiamine.
- wholegrains are rich however
-
High consumption of tea, coffee, fermented fish and betel nuts
- Contain thiaminases- break down thiamine in food
-
Malnutrition
- magnesium deifciency (cofactor)
- B1 deficiency
- Prolonged vomiting/ AWD
11
Q
How does alcohol abuse cause thiamine deficiency?
A
Alcohol blocks the active-transport mechanism for the absorption of thiamine in the GI tract
12
Q
What are the 2 types fo Beri-beri? Give examples of syndromes.
A
Dry beri beri
- nervous system involvment- peripheral neuropathy
- poor caloric intake and physical inactivity
- Wernicke’s encephalopathy and Korsakoff syndrome
Wet beri beri
- cardiovascular involvement
- Leads to high-output cardiac failure with peripheral vasodilation, peripheral oedema, and orthopnoea
13
Q
Summarise the epidemiology of vitamin B deficiency
A
Developed world-
- prevalence of Wernicke’s encephalopathy = 0.1-1%
- due to chronic alcohol abuse, in the context of poor nutritional intake
Developing-
- prevalence of B1 deficiency = 58-66% in East Asian countries
- Due to the large-scale consumption of thiamine-depleted polished rice.
14
Q
What are the presenting symtoms of wet beriberi?
A
Symptom of cardiac failure in wet beriberi due to acute or chronic deficiency:
- dyspnoea
- orthopnoea
- tachycardia, palpitations
- peripheral cyanosis
- peripheral oedema
15
Q
What are the presenting signs/symptoms of dry beriberi?
A
- Decreased sensation - distal peripheral polyneuropathy (particularly of the legs)
- Parasthesia
- Reduced knee jerks and other tendon reflexes
- Progressive severe muscle weakness with muscle wasting
16
Q
What is the triad of mental states in Wernicke’s encephalopathy?
A
- Acute confusion
- Ataxia
- Ocular abnormalities (e.g., nystagmus and strabismus).
NOTE: common, non-specific sign in patients presenting to hospital.
17
Q
A
18
Q
State some early signs of B1 deficiency
A
Fatigue
Muscle aches
19
Q
Generate a management plan for vitamin B deficiency
A
Thiamine replacement therapy-
- IV for acute, oral for alcohol withdrawal and F/U
- Pabrinex
- Magnesium, potassium, and phosphate adjunct
- If there is coexisting hypoglycaemia, ensure thiamine given before glucose
20
Q
Identify appropriate investigations for vitamin B deficiency
A
Diagnosis mainly clinical
Bloods:
-
erythrocyte thiamine pyrophosphate
- indicates thimaine stores
- takes time- used retrospectively to confirm diagnosis (Tx immediately)
- ABG + lactate- B1 deficiency is associated with lactic acidosis
21
Q
Summarise the prognosis for patients with vitamin B deficiency
A
Good if treated early, but Korsakoff is minimally reversible
22
Q
What is the outcome of severe vitamin C deficiency?
A
Scurvy
Most key clinical manifestations are related to impaired collagen synthesis.
23
Q
What are the consequences of vitamin C deficiency?
A
wound healing
immune function
iron absorption
24
Q
What are the commonest forms of Vit C deficiency?
A
- famine and refugee populations
- feeding infants on cow’s milk
- psychiatric disorders, alcohol abuse
- haemodialysis- dialyses vitamin C
- 3Ss- sepsis, smoking, surgery
- critical illness and acute hospitalisation
- pancreatitis
25
Recognise the presenting symptoms of vitamin C deficiency
_Other_
* **Gingivitis**, loose teeth, foul breath
* In children, **bone growth** may be impaired
_Constitutional symptoms:_
* arthralgia
* myalgia
* weakness, lethargy
* nausea, emesis
* weight loss
* dry skin
* depression
* dypsnoea
_Endothelial dysfunction and haemorrhage:_
* Easy **bruising, poor wound healing**
* **Petechial** and **perifollicular haemorrhages**
* **Oral mucosal petechiae**
* **coiled hairs**
_Manifestation of cardiac failure:_
* pedal **oedema**
* joint swelling
26
Identify appropriate investigations for vitamin C deficiency
Clinical diagnosis
* **FBC**
* **serum ascorbic acid**
* **Xray**- see corner fraction sign, a ground-glass appearance, trabecular atrophy, Pelkan's sign, Frankel's sign
27
What disease is precipitated by vitamin D deficiency in adults?
**Osteomalacia**
Metabolic bone disease characterised by **incomplete mineralisation** of **osteoid** following **growth plate closure** in adults
28
What disease is precipitated by vitamin D deficiency in children?
**Rickets**
Metabolic bone disease characterised by **defective mineralisation of the epiphyseal growth plate cartilage** in children
resulting in skeletal deformities and growth retardation.
29
What is considered vitamin D deficient? What is considered insufficient?
Serum **25-hydroxyvitamin D**
* **\<50** nanomoles/L = deficiency
* **52-72** nanomoles/L = insufficiency
30
What are the risk factors for vitamin D deficiency?
* **Lack of exposure to sunlight**
* sunscreen use
* season, latitude
* older people confined home
* Decreased Vit D GI absorption
* **Dietary deficiency**
* **Malabsorption**
* Deacreased pre-vitamin D synthesis in skin
* **age**
* **increased skin pigmentation**
* Decreased 25-hydroxylation of vitamin D
* l**iver disease**
* **anticonvulsants**
* Decrease 1a-hydroxylation of vitamin D
* **CKD**
* Enhanced metabolism of 25-hydroxy vit D:
* **primary hyperparathyroidism**
* **granulomatous disorders**- TB, sarcoidosis
* **obesity**- BMI \>30 = fat sequesters vitamin D
* **hyperthyroidism**
* **Tumour**- FGF23 - hypophosphataemia
31
List some drugs that can cause vitamin D deficiency
* glucocorticoids
* antiepileptic medication
* highly active ART
* rifampicin
* St John's wort
32
What is the name of the renal syndrome which can cause osteomalacia and what is its aetiology?
**Fanconi syndrome (renal tubular acidosis)**
Generalised dysfunction of the **renal PCT** that results in the urinary loss of:
* bicarbonate
* glucose
* amino acids
* phosphate
* small proteins and peptides
* organic acids and bases
33
Summarise the epidemiology of vitamin D deficiency and osteomalacia
**Most common nutritional deficiency**- worldwide 40% of children and adults are vitamin D deficient
More common in females
34
What are the presenting signs and symptoms of osteomalacia?
* **Fractures**
* occur with even mild trauma or movement
* commonly long bones
* **Diffuse bone pain and tenderness**
* lower extremities, lower spine, ribs, and pelvis
* **Proximal muscle weakness**
* associated with wasting
* Lead to a **waddling gait** and difficulty climbing stairs.
* **Mailaise**
* **Signs of hypocalcaemia**:
* Trousseau's sign,Chvostek's sign
35
What are the presenting signs and symptoms of rickets?
* **bone pain** (fractures)
* **swelling of costochondral junctions** (rickety rosary)
* **growth retardation** (FTT)
* **bony deformities**
* Bow legs in early childhood
* 'Knock knees' in later childhood
* Bossing of frontal and parietal bones
* **muscle weakness and hypotonia-** due to hypocalcaemia or hypophosphataemia
36
Identify appropriate blood test investigations for vitamin D deficiency
_Bloods_
* **serum 25-hydroxyvitamin D**
* **serum alkaline phosphatase** (normal-high)
* **serum calcium** (normal due to inc. PTH)
* **Check U&Es** (look for renal failure)
* **Check ABGs** (for renal tubular acidosis)
* **fasting serum phosphate** (secondary hyperparathyroidism)
* **PTH** (secondary hyperparathyroidism)
* normal in mild vitamin D deficiency and insufficiency- not good diagnostic marker
37
Identify the appropriate imaging investigations for osteomalacia/vitamin D deficiency and what you may see
1. **plain-film radiographs of knees and wrists**
* cupping, splaying, and fraying of the metaphysis
* Looser's zone (pseudofracture)- lucencies traversing partway at right angles
2. **DEXA**
* low BMD due to high serum PTH
3. **Iliac crest biopsy with double tetracycline labelling**
* ****definitive diagnostic test for osteomalacia
* you would see reduced distance between tetracycline bands = reduced mineralisation
38
Generate a management plan for vitamin D deficiency and osteomalacia
*Treat underlying cause*
1. Calcium + vitamin D
* **ergo/colecalciferol + calcium carbonate**
2. Vit D metabolite eg calcitriol + calcium carbonate if patient doesnt respond to primary treatment
*Monitor*:
* Serum calcium
* Phosphate
* ALP
* PTH
* Vitamin D
39
Identify possible complications of vitamin D deficiency and osteomalacia
_Common:_
* **Osteopenia/osteoporosis**
* secondary hyperparathyroidism → increase in bone resorption → decrease in BMD
* **Falls/fractures, deformities-** permanent in children
* **Depression**
* Complications of hypocalcaemia
_Increased risk of a number of chronic diseases:_
* **cancer**
* **autoimmune** diseases eg MS
* type 2 **diabetes**
* heart disease and hypertension
* **neurocognitive dysfunction**
* infectious diseases (URTI, TB)
* **osteoarthritis**
40
What are the symptoms of hypocalcaemia?
CATS go NUMB:
* Convulsions
* Arrhythmias
* Tetany
* Numbness/parasthesia
41
WHat are the risk factors of vitamin E deficiency?
* **cystic fibrosis**
* **abetalipoproteinemia**
* chronic **cholestatic hepatobiliary** disease
* **short bowel** syndrome
Impaired absorption of fat soluble vitamins
42
What is the outcome of vitamin E deficiency?
Both **central and peripheral nervous systems** are affected
Can have UMN or LMN findigns including:
* **Peripheral neuropathy**
* **Movement disorders-** muscle contractions, dysarthria, and muscle weakness
* **Cerebellar dysfunction** (e.g., ataxia, dysarthria, dysmetria),
* **Ocular disorders** such as ophthalmoplegia and retinitis pigmentosa
43
Epidemiology of vit E deficiency?
very rare
44
Recognise the presenting symptoms of vitamin E deficiency
* Weakness
* Loss of vibration sense
* Decline in visual field
45
Recognise the signs of vitamin E deficiency
* **Hyporeflexia**
* Decreaed **proprioception**
* **Distal muscle weakness**
* **Loss of vibration** sense
* **Ataxia**
* **Dysarthria**
* **Retinopathy**
* Compromise **immune system**
46
What are the risk factors for vitamin K deficiency?
* **Anticoagulants**
* **Dietry** deficiency
* **Antibiotics** which interfere with vit K absorption
* **Fat malabsorption** e.g. in coeliac disease, CF
* Infants at risk of breast milk low in vit K
47
Summarise the epidemiology of vitamin K deficiency
Rare in adults, more common in infants
48
Recognise the presenting symptoms of vitamin K deficiency
Vitamin K is important for coagulopathy so main symptom is excessive bleeding
* **Ecchymoses at non-traumatic sites**
* **Spontaneous bleeds**
* **Dark black,** tar like stool
* **Nose bleeds**
49
Identify appropriate investigations for vitamin K deficiency and interpret the results
* History
* Prothrombin time
50
How to manage vit K deficiency?
dietry supplements
check for liver dysfunction
51
State sme risk factors for B12 deficiency
* **\>65 years**
* **history of gastric surgery** (gastrectomy, or bypass for obesity)
* **vegan and vegetarian diet-** B12 found in animal protein
* **chronic GI illnesses** (e.g., Crohn's disease or coeliac disease)
* **Pernicious anaemia-** lack of IF
* medications -
* **PPIs**
* **H2 receptor antagonists**
* **metformin**
* **anticonvulsants**
52
What is required for absorption of B12 and where does this occur?
**Intrinsic factor**- produced by gastric parietal cells
occurs in the **terminal ileum**
53
What is haematological condition caused by lack of B12 and what is the commonest cause of this condition?
**megaloblastic anaemia**
80% of megaloblastic anaemia is caused by **pernicious anaemia**
**Autoimmune** condition involving gastritis, atrophy of all layers of the body and fundus of the stomach and **loss of normal gastric glands, parietal and chief cells**
No parietal cells = no IF = no B12 absorption
54
Summarise the epidemiology of vitamin B12 deficiency
* 39% of US adults at risk for vitamin B12 deficiency
* dietry deficiency more common in vegans/developing countries
55
Recognise the presenting symptoms of vitamin B12 deficiency
**Typical anaemia symptoms**
* Fatigue
* Lethargy
* Dyspnoea
* Faintness
* Palpitations
* Headache
* Petichiae
Neurological Symptoms
* **Paraesthesia**
* **Numbness, decreased vibration sense**
* **Cognitive changes**
* **Visual disturbances**
* **Ataxia**
56
Recognise the signs of vitamin B12 deficiency on physical examination
* **Pallor**
* **Heart failure** (can occur with severe anaemia)
* **Glossitis**
* **Angular stomatitis**
_Neuropsychiatric:_
* irritability
* dementia
* depression
_Neurological_
* **Subacute combined degeneration of the spinal cord**= positive Romberg's test
* **Peripheral neuropathy**
57
Identify appropriate investigations for vitamin B12 deficiency
NO gold standard for diagnosing vitamin B12 deficiency
Measurement of serum B12 is not very accurate or reliable
* **FBC and blood film**
* Hypersegmented neutrophils
* Oval macrocytes
* Circulating megaloblasts
* elevated MCV, low haematocrit
* **Pernicious Anaemia Tests**
* Anti-intrinsic factor antibodies
* Anti-parietal cell antibodies
* Schilling test
* **Reticulocyte count**
* differentiate B12 deficiency from haemolytic anaemia.
* low
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