Deficiency syndromes of water-soluble vitamins US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Deficiency syndromes of water-soluble vitamins. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Deficiency syndromes of water-soluble vitamins US Medical PG Question 1: A 34-year-old female with a past medical history of a gastric sleeve operation for morbid obesity presents for pre-surgical clearance prior to a knee arthroplasty. Work-up reveals a hemoglobin of 8.7 g/dL, hematocrit of 26.1%, and MCV of 106 fL. With concern for folate deficiency, she is started on high dose folate supplementation, and her follow-up labs are as follows: hemoglobin of 10.1 g/dL, hematocrit of 28.5%, and MCV of 96 fL. Given her history of gastric sleeve surgery and associated malabsorption risks, she is at long-term risk for which complication?
- A. Peripheral neuropathy (Correct Answer)
- B. Macular degeneration
- C. Hypothyroidism
- D. Microcytic anemia
- E. Neural tube defects
Deficiency syndromes of water-soluble vitamins Explanation: ***Peripheral neuropathy***
- Gastric sleeve surgery can lead to **vitamin B12 deficiency** due to the removal of the fundus, which produces **intrinsic factor** necessary for B12 absorption.
- **Vitamin B12 deficiency** is a known cause of **peripheral neuropathy**, manifesting as numbness, tingling, and weakness.
*Macular degeneration*
- This condition is primarily associated with **aging**, **genetics**, and **environmental factors** like smoking, rather than micronutrient deficiencies post-gastric sleeve.
- While certain vitamins (e.g., A, C, E) and minerals can influence macular health, there's no direct strong causal link between bariatric surgery malabsorption and increased risk of **macular degeneration**.
*Hypothyroidism*
- Hypothyroidism is most commonly caused by **autoimmune conditions** like Hashimoto's thyroiditis or **iodine deficiency**.
- While bariatric surgery can influence overall metabolic health, it does not directly lead to an increased risk of primary hypothyroidism.
*Microcytic anemia*
- **Microcytic anemia** is characterized by **small red blood cells (low MCV)**, typically caused by **iron deficiency** or **thalassemia**.
- The patient initially presented with **macrocytic anemia (MCV 106 fL)**, which improved with folate, but the underlying risk remains for macrocytic rather than microcytic anemia from malabsorption of B12 or folate.
*Neural tube defects*
- **Neural tube defects** are congenital anomalies that occur during early fetal development, primarily linked to **folate deficiency during pregnancy**.
- While the patient had a folate deficiency, this complication is relevant to **fetal development** and not a long-term risk for the adult patient herself after surgery.
Deficiency syndromes of water-soluble vitamins US Medical PG Question 2: A 55-year-old woman presents to her primary care physician with diarrhea. She states that it has persisted for the past several weeks and has not been improving. She also endorses episodes of feeling particularly flushed in the face. Her temperature is 99°F (37.2°C), blood pressure is 125/63 mmHg, pulse is 100/min, respirations are 15/min, and oxygen saturation is 97% on room air. Physical exam is notable for wheezing on pulmonary exam. The patient is discharged with medications for her symptoms. She returns 2 weeks later with symptoms of diarrhea, dry skin, a non-specific rash, and a notable decline in her memory. Which of the following is the most likely cause of this patient’s most recent presentation?
- A. Niacin deficiency (Correct Answer)
- B. Increased vasoactive intestinal peptide levels
- C. Increased catecholamine levels
- D. Vitamin B12 deficiency
- E. Increased serotonin levels
Deficiency syndromes of water-soluble vitamins Explanation: ***Niacin deficiency***
- The patient's **most recent presentation** with the **\"3 Ds\" of pellagra**—**dermatitis** (dry skin, rash), **diarrhea**, and **dementia** (memory decline)—is characteristic of **niacin (Vitamin B3) deficiency**.
- The initial presentation (diarrhea, flushing, wheezing) suggests **carcinoid syndrome** from a carcinoid tumor secreting **serotonin**.
- **Carcinoid tumors consume large amounts of tryptophan** to produce serotonin, thereby **depleting the tryptophan pool** needed for **endogenous niacin synthesis**.
- This leads to **secondary niacin deficiency (pellagra)**, especially in patients with carcinoid syndrome, making niacin deficiency the cause of the **most recent symptoms** after the initial carcinoid presentation.
*Increased vasoactive intestinal peptide levels*
- Elevated **vasoactive intestinal peptide (VIP)** levels are seen in **VIPomas**, causing **watery diarrhea, hypokalemia, and achlorhydria (WDHA syndrome)**.
- While diarrhea is present, VIPoma does not explain the **flushing, wheezing, or the subsequent development of pellagra** (dermatitis and dementia).
*Increased catecholamine levels*
- Increased **catecholamine levels** are characteristic of **pheochromocytoma**, presenting with **paroxysmal hypertension, headaches, palpitations, and diaphoresis**.
- This does not explain the **diarrhea, flushing, wheezing, or pellagra symptoms** seen in this patient.
*Vitamin B12 deficiency*
- **Vitamin B12 deficiency** causes **megaloblastic anemia, subacute combined degeneration** (posterior column and corticospinal tract findings), **peripheral neuropathy, and glossitis**.
- The prominent **diarrhea, flushing, wheezing, and dermatitis** are not consistent with B12 deficiency.
*Increased serotonin levels*
- While elevated **serotonin levels** from **carcinoid syndrome** explain the **initial presentation** (diarrhea, flushing, bronchospasm), they do not directly explain the **most recent presentation**.
- The question specifically asks about the cause of the **most recent symptoms** (dry skin, rash, memory decline), which represent **pellagra from niacin deficiency**—a known complication of carcinoid syndrome due to tryptophan depletion for serotonin synthesis.
- The **niacin deficiency** is the proximate cause of the new symptoms, making it the better answer for "most recent presentation."
Deficiency syndromes of water-soluble vitamins US Medical PG Question 3: A 35-year-old alcoholic patient presents with high-output cardiac failure, tachycardia, a bounding pulse, and warm extremities. Blood work reveals vitamin deficiency. Which of the following vitamin deficiencies is most likely associated with such a clinical presentation?
- A. Thiamine (Correct Answer)
- B. Riboflavin
- C. Vitamin B12
- D. Vitamin D
- E. Niacin
Deficiency syndromes of water-soluble vitamins Explanation: ***Thiamine***
- **Thiamine deficiency**, particularly in alcoholics, can lead to **wet beriberi**, characterized by **high-output cardiac failure** due to peripheral vasodilation, resulting in symptoms like tachycardia, bounding pulse, and warm extremities.
- Thiamine (vitamin B1) is a crucial cofactor in carbohydrate metabolism, and its deficiency impairs myocardial energy production and causes systemic vasodilation.
*Riboflavin*
- **Riboflavin deficiency** (ariboflavinosis) typically presents with **cheilosis**, glossitis, angular stomatitis, and seborrheic dermatitis, and is not directly associated with high-output cardiac failure.
- While it can occur in alcoholics, cardiac failure is not a prominent feature.
*Vitamin B12*
- **Vitamin B12 deficiency** primarily causes **megaloblastic anemia** and neurological symptoms such as **peripheral neuropathy**, ataxia, and cognitive impairment, rather than high-output cardiac failure.
- Cardiac manifestations are usually due to severe anemia leading to compensatory high output, but not the primary cause as seen in thiamine deficiency.
*Vitamin D*
- **Vitamin D deficiency** is associated with **osteomalacia** in adults and rickets in children, leading to bone pain, muscle weakness, and increased fracture risk.
- It does not cause high-output cardiac failure or related cardiovascular symptoms.
*Niacin*
- **Niacin deficiency** (pellagra) is characterized by the "3 Ds": **dermatitis**, **diarrhea**, and **dementia**, along with glossitis and stomatitis.
- While cardiovascular symptoms can occur in severe cases, high-output cardiac failure with a bounding pulse is not a typical hallmark of pellagra.
Deficiency syndromes of water-soluble vitamins US Medical PG Question 4: A 45-year-old man presents with lethargy, muscle aches, and dry skin. He is underweight and has very particular eating habits. Physical examination reveals swollen bleeding gums, cracked lips, petechiae, perifollicular hemorrhage, and corkscrew hairs. Laboratory tests reveal a nutritional deficiency. Which of the following is the key function of the most likely deficient nutrient?
- A. Hydroxylation of lysine and proline residues in collagen synthesis (Correct Answer)
- B. Precursor of serotonin
- C. Component of the visual pigment rhodopsin
- D. Gamma-carboxylation of glutamate residues in clotting factors
- E. Cofactor in carboxylase reactions
Deficiency syndromes of water-soluble vitamins Explanation: ***Hydroxylation of lysine and proline residues in collagen synthesis***
- The patient's symptoms of **swollen, bleeding gums**, **petechiae**, **perifollicular hemorrhage**, and **corkscrew hairs** are classic signs of **scurvy**, caused by a severe deficiency of **vitamin C**.
- **Vitamin C** (ascorbic acid) is a crucial **cofactor** for **prolyl hydroxylase** and **lysyl hydroxylase**, enzymes essential for the hydroxylation of **proline** and **lysine** residues in **collagen** synthesis, which stabilizes the collagen triple helix.
*Precursor of serotonin*
- **Serotonin** is synthesized from the amino acid **tryptophan**, not vitamin C.
- Deficiency of serotonin precursors is not associated with the bleeding and connective tissue problems observed in this patient.
*Component of the visual pigment rhodopsin*
- **Rhodopsin** is a visual pigment found in the retina, and its formation requires **vitamin A** (retinol).
- Deficiency of vitamin A leads to **night blindness** and xerophthalmia, not the symptoms described.
*Gamma-carboxylation of glutamate residues in clotting factors*
- This process is essential for the activation of several **blood clotting factors** (II, VII, IX, X) and is dependent on **vitamin K**.
- Vitamin K deficiency can lead to bleeding diathesis, but the specific mucocutaneous and follicular signs point away from this.
*Cofactor in carboxylase reactions*
- **Biotin** (vitamin B7) acts as a cofactor for **carboxylase enzymes**, which are involved in fatty acid synthesis, gluconeogenesis, and amino acid metabolism.
- While biotin deficiency can cause skin and hair problems, it does not typically present with the specific bleeding and perifollicular hemorrhages seen with scurvy.
Deficiency syndromes of water-soluble vitamins US Medical PG Question 5: A 10-year-old boy is brought into your clinic by his mother for sunburns that have not been healing. The mother states that he easily gets sunburned. The mother admits she gave birth to him at home and has never taken him to see a doctor. The patient walks with a wide stance gait and appears unstable on his feet. He has an extensive erythematous, scaling, hyperkeratotic rash on his face, neck, arms and legs. After extensive workup, the patient is found to have a genetic disorder that results in defective absorption of an important vitamin. Which of the following is likely to be low if measured?
- A. Vitamin K
- B. Niacin (Correct Answer)
- C. Folate
- D. Vitamin A
- E. Vitamin B12
Deficiency syndromes of water-soluble vitamins Explanation: ***Niacin***
- The constellation of **sunburns that don't heal**, a **wide-stanced unstable gait**, and an **erythematous, scaling, hyperkeratotic rash** (consistent with dermatitis) strongly suggests **pellagra**.
- Pellagra is caused by a deficiency of **niacin (Vitamin B3)**, which is characterized by the "3 Ds": **dermatitis**, **diarrhea**, and **dementia (or neurological symptoms like ataxia)**.
*Vitamin K*
- Deficiency typically leads to **bleeding disorders** due to impaired coagulation, which is not indicated by the patient's symptoms.
- While newborns often receive a **vitamin K shot**, his current symptoms are unrelated to its deficiency.
*Folate*
- Folate deficiency primarily causes **megaloblastic anemia** and can lead to **neural tube defects** in developing fetuses.
- It does not explain the characteristic dermatological and neurological symptoms described.
*Vitamin A*
- Vitamin A deficiency is known to cause **night blindness** and **xerophthalmia** (dry eyes), and impaired immune function.
- While it plays a role in skin health, the specific rash and gait abnormalities point away from primary vitamin A deficiency.
*Vitamin B12*
- Deficiency leads to **megaloblastic anemia** with **neurological symptoms** such as peripheral neuropathy, but the dermatological manifestations (scaling, hyperkeratotic rash) and unhealing sunburn are not typical.
- The gait could be linked to neurological symptoms, but the overall presentation is better explained by niacin deficiency.
Deficiency syndromes of water-soluble vitamins US Medical PG Question 6: A 24-year-old man presents to the emergency department complaining of a prolonged course of diarrhea. He reports that he has had 3–4 large volume watery stools daily for the last several weeks. He has no pain with bowel movements, no abdominal pain, and no blood in his stools. He is homeless and uses recreational drugs. He also reports that he usually drinks a half-liter of whiskey, or whatever else he can find, every day and he has done this for several years. The physical exam is notable for a hyperpigmented rash across his face, neck, chest, and the backs of his hands and forearms. On mental status exam, he is oriented to person and place but not time; he scores a 23/30 on the Montreal Cognitive Assessment (MOCA). This patient's presentation is most likely related to which of the following micronutrients?
- A. Vitamin B2
- B. Vitamin B12
- C. Vitamin D
- D. Vitamin C
- E. Vitamin B3 (Correct Answer)
Deficiency syndromes of water-soluble vitamins Explanation: ***Vitamin B3***
- The patient's symptoms—diarrhea, dermatitis (hyperpigmented rash), and dementia (disorientation to time, MOCA 23/30)—are the classic **3 Ds of pellagra**, which is caused by a **vitamin B3 (niacin) deficiency**.
- His chronic alcohol use and poor nutritional status (homelessness, recreational drug use) put him at high risk for such a deficiency, as alcohol impairs nutrient absorption and niacin is often lacking in the diets of those with limited food access.
*Vitamin B2*
- Deficiency in **vitamin B2 (riboflavin)** typically presents with cheilosis, angular stomatitis, glossitis, seborrheic dermatitis, and ocular symptoms like corneal vascularization, none of which are specifically mentioned here.
- While chronic alcohol use can also cause riboflavin deficiency, the patient's full symptom complex points more strongly to pellagra.
*Vitamin B12*
- **Vitamin B12 deficiency** often leads to **macrocytic anemia**, neurological symptoms including peripheral neuropathy, ataxia, and cognitive impairment, and glossitis, but it does not typically cause the characteristic dermatologic rash or diarrhea seen in this patient.
- While chronic alcohol use is a risk factor, the specific triad of diarrhea, dermatitis, and dementia is not consistent with B12 deficiency.
*Vitamin D*
- **Vitamin D deficiency** is associated with bone health issues (rickets in children, osteomalacia in adults), muscle weakness, and in severe cases, hypocalcemia.
- It does not present with the specific combination of diarrhea, hyperpigmented rash, and cognitive changes described in the patient.
*Vitamin C*
- **Vitamin C deficiency (scurvy)** typically manifests as perifollicular hyperkeratosis, bleeding gums, petechiae, impaired wound healing, and musculoskeletal pain.
- While malnourishment and alcohol abuse increase the risk of scurvy, the patient's symptoms do not align with the classic presentation of vitamin C deficiency.
Deficiency syndromes of water-soluble vitamins US Medical PG Question 7: A 17-year-old high school student presents to your office for recent mood and skin changes. The patient is a high school senior who is competing on the wrestling team and recently has lost weight to drop two weight classes over the past several months. He states he has dry, cracking, and irritated skin, as well as a sensation of tingling in his hands and feet. The patient also states that he has not been feeling himself lately. He finds himself more irritable and no longer enjoys many of the activities he once enjoyed. He finds that he often feels fatigued and has trouble concentrating. The patient does not have a significant past medical history and is not on any current medications. The patient admits to drinking alcohol and smoking marijuana on special occasions. He states that he uses supplements that his other team members use. Physical exam is significant for acne, dry, cracked skin around the patient's mouth in particular, and decreased sensation in his lower extremities. Laboratory values are as follows:
Serum:
Na+: 137 mEq/L
Cl-: 101 mEq/L
K+: 4.1 mEq/L
HCO3-: 24 mEq/L
BUN: 15 mg/dL
Glucose: 79 mg/dL
Creatinine: 0.9 mg/dL
Ca2+: 9.2 mg/dL
Mg2+: 1.5 mEq/L
Homocysteine: 11.2 µmol/L (normal: 4.6 to 8.1 µmol/L)
AST: 11 U/L
ALT: 11 U/L
Alkaline phosphatase: 27 U/L
Albumin: 4.5 g/dL
Total protein: 6.9 g/dL
Total bilirubin: 0.5 mg/dL
Direct bilirubin: 0.3 mg/dL
Which of the following is the most likely diagnosis?
- A. Depression secondary to dietary changes
- B. Anabolic steroid use
- C. Dermatologic fungal infection
- D. Viral infection
- E. Water soluble vitamin deficiency (Correct Answer)
Deficiency syndromes of water-soluble vitamins Explanation: ***Water soluble vitamin deficiency***
- The patient's symptoms (irritability, fatigue, poor concentration, dry cracking skin around the mouth, tingling in hands and feet) coupled with a history of rapid weight loss for wrestling ("cutting weight") and elevated **homocysteine** levels are highly suggestive of a vitamin deficiency, specifically **B vitamins** (e.g., B6, B9, B12) which are water-soluble and easily depleted with poor dietary intake and increased metabolic demand.
- The elevated **homocysteine** is a key indicator, as vitamins B6, B9 (folate), and B12 are crucial cofactors in its metabolism. Deficiencies in these vitamins lead to hyperhomocysteinemia, which can cause neurological symptoms and skin manifestations.
*Depression secondary to dietary changes*
- While the patient exhibits mood changes (irritability, anhedonia, fatigue), these symptoms are better explained within the context of **nutritional deficiency**, which can directly impact neurotransmitter synthesis and overall neurological function.
- Depression alone would not typically account for the specific dermatological findings (**dry, cracking skin around the mouth**) or the **peripheral neuropathy** (tingling, decreased sensation) in conjunction with elevated homocysteine.
*Anabolic steroid use*
- Anabolic steroid use can cause **acne** and mood changes (irritability, aggression), but typically does not cause **dry, cracking skin around the mouth** or specific **tingling/numbness** in the extremities or elevated **homocysteine levels**.
- While the patient admits to using supplements, there's no direct evidence to suggest anabolic steroid use, and the constellation of symptoms points more strongly to a nutritional cause.
*Dermatologic fungal infection*
- A fungal infection might explain some skin changes, but it would not account for the systemic symptoms like **mood changes**, **fatigue**, **tingling in the hands and feet**, or the elevated **homocysteine**.
- The description of "dry, cracking skin around the patient's mouth" is more consistent with **cheilosis** or **angular stomatitis**, commonly associated with B vitamin deficiencies, rather than a typical fungal infection.
*Viral infection*
- A viral infection could cause **fatigue** and general malaise, but it would not explain the specific skin findings like **dry, cracking skin around the mouth**, **tingling in hands and feet**, or the elevated **homocysteine** levels, which are long-standing signs of nutritional deficiencies.
- The patient's symptoms have been ongoing for "several months," which is less typical for an acute viral illness.
Deficiency syndromes of water-soluble vitamins US Medical PG Question 8: A 55-year-old woman is brought to the physician by her daughter because of progressive memory loss and weakness over the past 6 months. She is now unable to perform activities of daily living and has had several falls in her apartment. She has diarrhea but has not had nausea or vomiting. She was treated for tuberculosis 10 years ago. She smoked half a pack of cigarettes daily for 25 years but stopped 8 years ago. She drinks a pint of vodka daily. Vital signs are within normal limits. Examination shows glossitis and a hyperpigmented rash on her face and arms. There are multiple bruises over both arms. On mental status examination, she is oriented to place and person only. Short-term memory is impaired; she can recall 0 out of 5 objects after 10 minutes. Which of the following deficiencies is most likely present in this patient?
- A. Vitamin B2 (riboflavin)
- B. Vitamin B3 (niacin) (Correct Answer)
- C. Vitamin B7 (biotin)
- D. Vitamin B6 (pyridoxine)
- E. Vitamin B5 (pantothenic acid)
Deficiency syndromes of water-soluble vitamins Explanation: ***Vitamin B3 (niacin)***
- This patient presents with the classic **"4 Ds" of pellagra**: **Dermatitis** (hyperpigmented, photosensitive rash on sun-exposed areas - face and arms), **Diarrhea**, **Dementia** (progressive memory loss, disorientation, impaired short-term memory, inability to perform ADLs), and potentially Death if untreated.
- Her history of chronic **alcoholism** (pint of vodka daily) is the most significant risk factor for niacin deficiency, as alcohol impairs nutrient absorption, decreases dietary intake, and interferes with the conversion of tryptophan to niacin.
- **Glossitis** is also commonly seen in pellagra.
*Vitamin B2 (riboflavin)*
- Deficiency typically presents with **cheilosis**, angular stomatitis, glossitis, seborrheic dermatitis, and ocular symptoms like corneal vascularization.
- While **glossitis** is present, the prominent photosensitive rash, diarrhea, and severe dementia are characteristic of pellagra, not riboflavin deficiency.
*Vitamin B7 (biotin)*
- Biotin deficiency is rare and typically causes **dermatitis** (often periorificial), **alopecia**, and neurological symptoms like depression, lethargy, or paresthesias.
- It does not present with the classic "4 Ds" complex or the photosensitive distribution of rash seen in this patient.
*Vitamin B6 (pyridoxine)*
- Deficiency can cause **seborrheic dermatitis**, cheilosis, glossitis, peripheral neuropathy, and sideroblastic anemia.
- While some mucocutaneous symptoms overlap, it does not typically present with the photosensitive hyperpigmented rash, severe diarrhea, and progressive dementia characteristic of pellagra.
*Vitamin B5 (pantothenic acid)*
- Deficiency is extremely rare and usually presents with non-specific symptoms such as fatigue, irritability, sleep disturbances, numbness, and gastrointestinal complaints.
- It is not associated with the classic tetrad of dermatitis, diarrhea, dementia, and death.
Deficiency syndromes of water-soluble vitamins US Medical PG Question 9: A previously healthy 18-year-old woman comes to the physician because of a 2-day history of swelling and itchiness of her mouth and lips. It decreases when she eats cold foods such as frozen fruit. Four days ago, she underwent orthodontic wire-placement on her upper and lower teeth. Since then, she has been taking ibuprofen twice daily for the pain. For the past 6 months, she has been on a strict vegan diet. She is sexually active with one partner and uses condoms consistently. She had chickenpox that resolved spontaneously when she was 6 years old. Her vitals are within normal limits. Examination shows diffuse erythema and edema of the buccal mucosa with multiple serous vesicles and shallow ulcers. Stroking the skin with pressure does not cause blistering of the skin. The remainder of the examination shows no abnormalities. Which of the following is the most likely cause of these symptoms?
- A. Vitamin deficiency
- B. Dermatitis herpetiformis
- C. Allergic contact dermatitis (Correct Answer)
- D. Reactivation of varicella zoster virus
- E. Herpes labialis
Deficiency syndromes of water-soluble vitamins Explanation: ***Allergic contact dermatitis***
- The symptoms of **swelling, itchiness**, and **erythema of the buccal mucosa** with vesicles and shallow ulcers, occurring after orthodontic wire placement, strongly suggest an allergic reaction to materials in the wires (e.g., nickel).
- The improvement with **cold foods** (vasoconstriction and soothing effect) and the absence of skin blistering with pressure (differentiating from bullous diseases) further support this diagnosis.
*Vitamin deficiency*
- While a **vegan diet** can predispose to certain vitamin deficiencies (e.g., B12), the sudden onset of localized oral swelling and itchiness is not typical.
- Oral manifestations of vitamin deficiencies usually develop chronically and involve conditions like **glossitis, angular cheilitis, or stomatitis**, rather than acute localized swelling and vesicles.
*Dermatitis herpetiformis*
- This condition is characterized by intensely pruritic, vesicular lesions, primarily on **extensor surfaces** (elbows, knees, buttocks), and is strongly associated with **celiac disease**.
- Oral lesions are uncommon, and the lack of systemic GI symptoms or characteristic skin distribution makes this diagnosis less likely.
*Reactivation of varicella zoster virus*
- Reactivation (shingles) typically causes a **unilateral, dermatomal rash** with painful vesicles, usually occurring in older or immunocompromised individuals.
- The patient's age and healthy status, along with the bilateral involvement of the mouth and lips, do not fit the typical presentation of zoster reactivation.
*Herpes labialis*
- Caused by **Herpes Simplex Virus (HSV)**, it presents as clusters of painful vesicles, typically on the **lips or perioral region**.
- While vesicles are present, the diffuse erythema and edema of the buccal mucosa and the clear association with orthodontic hardware placement make allergic contact dermatitis a more likely etiology.
Deficiency syndromes of water-soluble vitamins US Medical PG Question 10: A 22-year-old primigravid woman comes to the physician for her initial prenatal visit at 12 weeks' gestation. She has had generalized fatigue and shortness of breath over the past 2 months. She has also had a tingling sensation in her toes for the past month. Three years ago, she was treated for gonorrhea. She follows a strict vegan diet since the age of 13 years. Her temperature is 37°C (98.6°F), pulse is 111/min, and blood pressure is 122/80 mm Hg. Examination shows pale conjunctivae and a shiny tongue. Muscle tone and strength is normal. Deep tendon reflexes are 2+ bilaterally. Sensation to vibration and position is decreased over the upper and lower extremities. When asked to stand, hold her arms in front of her, and close her eyes, she loses her balance and takes a step backward. Which of the following is most likely to have prevented this patient's condition?
- A. Calcium supplementation
- B. Thyroxine supplementation
- C. Vitamin B12 supplementation (Correct Answer)
- D. Iron supplementation
- E. Penicillin G therapy
Deficiency syndromes of water-soluble vitamins Explanation: ***Vitamin B12 supplementation***
- The patient's symptoms, including **fatigue**, **shortness of breath**, **tingling sensation in toes** (paresthesias), **pale conjunctivae**, **shiny tongue** (glossitis), decreased **vibration and position sensation**, and **ataxia** (losing balance with eyes closed), are classic signs of **vitamin B12 deficiency**.
- A **strict vegan diet** since age 13 significantly increases the risk of vitamin B12 deficiency, as B12 is primarily found in animal products. Supplementation would have prevented these symptoms.
*Calcium supplementation*
- **Calcium** is essential for bone health, muscle function, and nerve transmission, but deficiency typically causes symptoms like **osteoporosis**, **muscle cramps**, or **tetany**, not the specific neurological and hematological signs seen here.
- While important in pregnancy, calcium deficiency does not explain the patient's array of symptoms, especially the neurological presentation.
*Thyroxine supplementation*
- **Thyroxine** (thyroid hormone) deficiency (hypothyroidism) can cause fatigue, but symptoms typically also include **weight gain**, constipation, cold intolerance, and dry skin, which are not mentioned.
- It does not cause the specific neurological signs like **paresthesias**, loss of **vibration sensation**, or **ataxia**, nor does it explain the **shiny tongue**.
*Iron supplementation*
- **Iron deficiency** is a common cause of fatigue, shortness of breath, and pale conjunctivae (due to anemia). However, it does not typically cause the **neurological symptoms** described (tingling, sensory loss, ataxia) or the **shiny tongue**.
- Although iron deficiency anemia might coexist, the neurological findings strongly point away from it as the primary cause of all symptoms.
*Penicillin G therapy*
- **Penicillin G** is used to treat bacterial infections, including syphilis and gonorrhea. While the patient was treated for gonorrhea, this current presentation is not indicative of an active infection.
- The symptoms are characteristic of a nutritional deficiency, not a bacterial infection or a complication of prior gonorrhea without current active infection.
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