A 18-month-old child presents with follicular hyperkeratosis, perifollicular hemorrhages, bleeding gums, and loose teeth. Another child of the same age has hypocalcemia, tetany, and delayed tooth eruption with enamel hypoplasia. Which finding best distinguishes vitamin C deficiency from vitamin D deficiency in these two children?

## Distinguishing Vitamin C from Vitamin D Deficiency by Clinical Features ### The Hemorrhagic Signature of Scurvy **Key Point:** Perifollicular hemorrhages and bleeding gums are **pathognomonic for vitamin C deficiency (scurvy)** and are absent in vitamin D deficiency. This is the single best clinical discriminator. ### Comparative Clinical Features | Feature | Vitamin C Deficiency (Scurvy) | Vitamin D Deficiency (Rickets) | |---------|-------------------------------|-------------------------------| | **Perifollicular hemorrhages** | **Present (hallmark)** | Absent | | **Bleeding gums** | **Present (friable, swollen)** | Absent | | **Follicular hyperkeratosis** | **Present** | Absent | | **Hypocalcemia** | Absent | Present | | **Tetany/seizures** | Absent | Present | | **Tooth eruption** | Normal timing | Delayed | | **Enamel hypoplasia** | Absent | Present | | **Subperiosteal hemorrhages** | **Present on X-ray** | Absent | **High-Yield:** The **hemorrhagic manifestations** (perifollicular hemorrhages, bleeding gums, follicular hyperkeratosis) are exclusive to vitamin C deficiency and do NOT occur in rickets. ### Mnemonic for Scurvy Bleeding **Mnemonic:** **SCURVY** = **S**ubperiosteal hemorrhages, **C**ontact bleeding (gums), **U**nhealed wounds, **R**ash (perifollicular), **V**itamin C deficiency, **Y**ellow-tinged skin ### Why Hypocalcemia Is NOT the Discriminator **Warning:** While hypocalcemia and tetany are classic features of severe vitamin D deficiency, they are **absent in scurvy**. However, hypocalcemia is a **secondary metabolic consequence** of rickets, not a primary tissue manifestation. The hemorrhagic signs are **primary tissue-level defects** specific to vitamin C deficiency and thus more reliable discriminators. ### Clinical Pearl **Clinical Pearl:** A child with bleeding gums and perifollicular hemorrhages has scurvy until proven otherwise. Vitamin D deficiency never causes bleeding; it causes metabolic derangements (hypocalcemia) and skeletal deformity instead. [cite:Park 26e Ch 6; Harrison 21e Ch 75]