A Guide To Dry Skin Disorders In The Lower Extremity
Aged/elderly skin. In elderly skin, the epidermis thins and the corneocytes do not adhere to each other as well and the skin loses its water-binding capacity. Dry skin is itchy skin and itchy skin is dry skin. It is difficult to split them up. Itching in the elderly presents a diagnostic and therapeutic challenge. A thorough history, review of systems and physical examination are critical to determining the cause of itching.
Examination of the skin may be misleading. There are frequently only secondary lesions, eczematous changes, lichenification and excoriation, which we may misdiagnose as a primary dermatitis. Xerosis may be the cause but it is sometimes merely coincidental. If primary lesions are present, a skin biopsy can aid in diagnosis. Consider systemic causes of itching such as cholestasis, uremia, hyperthyroidism, medications or lymphoma.
If the cause remains elusive, consider idiopathic itching of the elderly or so-called “senile pruritus.” The pathophysiology of this form of pruritus is poorly understood but it is likely that age-related changes of the skin, cutaneous nerves and other parts of the nervous system play a role.22
Treating Dry Skin That Is Concomitant With Common Diseases
Certain disease states can cause xerosis so in the workup, one should make note of congenital and acquired ichthyoses, atopic dermatitis, hypothyroidism, Down syndrome, renal failure, malnutrition, malabsorption, HIV, lymphoma, liver disease, Sjögren’s syndrome and certain drugs.
End-stage renal disease (ESRD). This is a progressive and irreversible kidney dysfunction lasting three months or more. Nearly all patients with ESRD have at least one dermatological disorder, and these skin and nail changes can occur before or even after initiation of dialysis or transplantation.23 Some authors have suggested that ESRD–associated xerosis may be a result of decreased water content in the epidermis. Clinical and histologic evaluations have shown an overall decrease in sweat volume in patients with uremia as well as the atrophy of sebaceous glands.24
Xerosis occurs in 50 to 75 percent of dialysis patients.24 It manifests as poor skin turgor with scaling, dryness and fissuring of the skin, particularly affecting extensor surfaces of extremities.
Of those with chronic renal failure, 15 to 49 percent experience pruritus. Of those patients undergoing dialysis, the prevalence is up to 50 to 90 percent but as dialysis has improved, it has become less common.24 In acute renal failure, pruritus is very uncommon. The pruritus of ESRD is most often generalized and light, but can be severe and unremitting.23
Hypothyroidism. Hypothyroidism is more common in women and people over the age of 50. The thyroid produces too few thyroid hormones and this reduces the activity of the sweat and oil glands, leading to rough, dry skin. Symptoms with a high specificity for hypothyroidism include constipation, cold intolerance, proximal muscle weakness, hair thinning and dry skin. Dry skin can be a symptom of hypothyroidism in infants and children as well. A blood test can determine the level of thyroid stimulating hormone as well as thyroid hormones T3 and T4.
Diabetes. People with diabetes have a high incidence of xerosis of the feet, especially on the heels. While assessing for predictors of foot lesions in patients with diabetes, one study found that 82.1 percent of their patients had skin with dryness, cracks or fissures.25 An unpublished survey of 105 consecutive patients with diabetes conducted by one of the authors revealed that 75 percent had clinical manifestation of dry skin. Dry skin often leads to cracks and fissures, which can serve as a portal of entry for bacteria.