Vitamin C

Introduction to Vitamin C Hypovitaminosis (Scurvy)

Inadequate intake of Vitaminum C in the human body triggers a cascade of pathological reactions that ultimately form the full clinical picture of scorbutus (scurvy). This condition is characterized by systemic involvement of various organs and tissues. At the initial stages of vitamin C hypovitaminosis development, general, non-specific symptoms come to the fore, significantly reducing the patient's quality of life.

These basic clinical manifestations include:

• Pronounced irritability, indicating the involvement of the nervous system in the pathological process.
• Dyspnea, which may trouble the patient even at relative rest or during minor physical exertion.
• Anorexia, manifested as a persistent decrease or complete loss of appetite.
• Subfebrile temperature — a prolonged increase in body temperature to subfebrile values, indicating a systemic reaction of the body to the developing deficiency.

Specific bone-hemorrhagic manifestations of scurvy

As vitamin C hypovitaminosis progresses, more severe and specific symptoms develop, affecting the vascular bed and musculoskeletal system. These signs are key to making a diagnosis.

1. Hemorrhagic syndrome: due to impaired vascular permeability, patients develop extensive hematomas. According to clinical data, hemorrhages are localized predominantly intramuscularly, as well as beneath the periosteum (so-called subperiosteal hematomas).
2. Bone deformations: a pronounced and extremely painful enlargement of the epiphyses of tubular bones is observed.
3. Chest alterations: specific thickenings known as a "rosary" form on the ribs. Visually, they strongly resemble similar formations occurring in rickets, but in scurvy, these costal "beads" have a significantly sharper shape.

Etiology of acquired biotin deficiency

Biotin hypovitaminosis is studied in close connection with the topic of vitamin deficiency. Unlike many other conditions, biotin deficiency is strictly acquired in nature. Pathological physiology identifies two main causes (etiology) for the development of this disease:

• Alimentary cause: associated with dietary features, specifically the consumption of excessively large amounts of raw egg white. Raw egg white contains a specific glycoprotein, avidin. Upon entering the digestive tract, avidin tightly binds biotin, forming an insoluble complex, making the absorption of the vitamin into the bloodstream impossible.
• Iatrogenic cause: caused by the long-term administration of certain groups of medications, primarily sulfonamides and antibiotics. These drugs cause a powerful suppression of the growth and reproduction of normal intestinal microflora. Since it is normally intestinal bacteria that synthesize a significant portion of the biotin required by the body, their death naturally leads to the development of hypovitaminosis.

Systemic clinical manifestations of biotin deficiency

The clinical picture of acquired biotin deficiency is extremely diverse and affects several major body systems simultaneously. The symptom complex includes the following groups of disorders:

• Dermatological manifestations: patients develop severe dermatitis. They are accompanied by excessive production of sebaceous gland secretion, leading to seborrhea. In addition, active hair loss (alopecia) and pathological brittleness of the nail plates are observed.
• Muscular manifestations: intense muscle pain, designated by the term myalgia, is a characteristic symptom.
• Hematological manifestations: various types of anemia are registered in the blood system, indicating impaired hematopoiesis.
• Neurological manifestations: the central nervous system suffers, which in clinical practice is expressed as the development of profound clinical depression.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Pathogenesis of the formation of subperiosteal and intramuscular hematomas in scurvy.
• Mechanisms of development of anorexia and subfebrile fever against the background of vitamin C deficiency.
• Biochemical interaction of the glycoprotein avidin and biotin in the intestine.
• Types of anemia developing in biotin hypovitaminosis and their hematological picture.
• Differential diagnosis of dermatitis, seborrhea, and alopecia in vitamin deficiency.

Other topics in "Chapter 14. Vitamin Metabolism Disorders"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.