Scurvy

Scurvy is a disease caused by a deficiency of vitamin C (ascorbic acid), necessary for the synthesis of collagen in humans. The chemical name for vitamin C, ascorbic acid, comes from the Latin root scorbutus. It was common in seafarers who subsisted on diets that contained no fresh fruit or vegetables (replacing these with dried grains and salted meat).

The Scottish naval physician James Lind, who lived in the 18th century, is often credited with identifying the cause of scurvy and how to prevent and cure it by adding citrus fruits to the diet.

However, the Spanish were already aware of the use of citrus fruits as a remedy since the second half of the 16th century, more than 100 years before the birth of James Lind, thanks to the treaty of Fray Agustín Farfán in 1579 under the title Brief treatise on anatomy and surgery, and some diseases where the use of oranges and lemons is recommended for the treatment of scurvy.

Etymology

The word came into Spanish through French scorbute, from its origin in the Netherlands, from Middle Low Saxon schorbûk or Early Modern Dutch schorbuyck , which means roughly 'belly rupture'.

Pathophysiology

The normal synthesis of collagen depends on the correct hydroxylation of lysine and proline (to obtain hydroxyproline and hydroxylysine) in the endoplasmic reticulum. Said hydroxylation is carried out by lysyl hydroxylase and prolyl hydroxylase, enzymes that require ascorbic acid (vitamin C) as a coenzyme. The deficiency of ascorbic acid prevents the correct hydroxylation of these, therefore defective procollagen chains are obtained and the synthesis cannot be completed correctly.

Clinical manifestations

Characteristics of the disease include hyperkeratotic perifollicular papules in which the hairs fragment and fall out; perifollicular hemorrhages; purpura that begins in the posterior part of the lower extremities and ends up converging and forming ecchymoses; hemorrhages in the muscles of the arms and legs with secondary phlebothrombosis; intra-articular hemorrhages; splinter hemorrhages in nail beds; gum involvement, especially in people with teeth that include swelling, friability, bleeding, secondary infections, and loosening of the teeth; poor wound healing and reopening of recently healed ones; petechial hemorrhages in the viscera; and emotional disturbances. Symptoms similar to those of Sjögren's syndrome may appear.

In terminal stages, jaundice, edema, and fever are common, and convulsions, shock, and death may occur suddenly.

Laboratory data

Normochromic and normocytic anemia, due to tissue hemorrhages, is common. Anemia can be macrocytic or megaloblastic in one fifth of patients. Many of the foods that contain vitamin C also contain folates, and diets that cause scurvy can also induce folate deficiency. However, ascorbic acid deficiency also produces increased oxidation of formyl tetrahydrofolic acid to inative folate metabolites. It is not known exactly whether an alteration in the distribution and storage of iron is also involved in the pathogenesis of anemia. The anemia is corrected with the contribution of vitamin C and with the establishment of a balanced diet.

Diagnosis

In some hospitals, the determination of ascorbic acid levels in platelets is used to establish the diagnosis of scurvy, since in this disease its value is usually less than a quarter of the normal value. Plasma levels of the vitamin have a worse correlation with the clinical state. In infants, radiological bone abnormalities can be diagnosed. Bilirubin is often elevated. Capillary fragility is normal.

Treatment

The usual dose of vitamin C in adults is 100 mg three to five times daily by mouth until 4 grams have been administered, followed by 100 mg/day afterward. In infants and young children, the appropriate dosage is 10 to 25 mg three times daily. At the same time, a diet rich in vitamin C is established. Spontaneous bleeding usually stops in 24 hours, muscle and bone pain subsides quickly, and the gums begin to heal in two to three days. Even large bruises or ecchymoses return in 10 to 12 days, although pigmentary changes in areas of heavy bleeding may persist for months. Serum bilirubin normalizes in three to five days, and anemia is usually corrected in two to four weeks or months.

Scurvy in Animals

Most animal species are capable of synthesizing vitamin C, as they possess the enzyme L-gulonolactone oxidase, (GULO, for its acronym in English). As notable exceptions, we can cite most of the bats, and higher primates that are taxonomically closely related to humans, specifically the Anthropoidea (Haplorrhini) suborder, which includes tarsiforms and apes. Two species of Caviidae, the capybara and the guinea pig, do not synthesize ascorbic acid either. Various sources contradict each other regarding scurvy in companion animals, such as dogs and cats.