The role of metal patch testing in evaluating patients for metallic prosthetic joint failure.

BACKGROUND: Metal allergy may be an uncommon cause of prosthetic joint failure. There exist little data on patch testing to metals in this context and its impact on outcomes of joint revision in these patients. OBJECTIVE: To explore the use and indications for metal patch testing in the evaluation of patients suspected of having metal allergy as a cause of failed joint replacements and to clarify the outcomes of patients revised with alternative metallic joints because of positive patch testing result. METHODS: A retrospective analysis from January 2016 to April 2020 was completed on a patient cohort referred for evaluation of metal hypersensitivity. Charts were reviewed for age, biological sex, referring specialty, patch testing results, joint, revision status, and outcome measures. Biostatistical analysis and descriptive statistics were performed to determine patch testing performance and functional outcome trends among this patient cohort. RESULTS: The sensitivity and specificity of patch testing, in general, are limited when evaluating patients with metallic joint replacements. However, the predictive value of testing seemed to improve with strongly positive patch testing results. Functional outcomes in patients when positive results were used to guide revision prosthesis revealed clinical improvement. CONCLUSION: The attribution of metal allergy or hypersensitivity as a cause of failure in metal prosthetic joint replacement remains unproven. Some patients with positive histories and patch testing results that were used to modify the implanted prosthesis had improved functional outcomes. These results suggest that patch testing may be useful in patients with history of metal sensitivity and prosthetic failure.

Chronic urticaria: pathophysiology and etiology, or the what and why.

Chronic urticaria (CU) is a relatively common but vexing disease. The pathophysiology is based on the cutaneous mast cell release of mediators, predominantly histamine. Release can be induced via specific immunoglobulin E (IgE), components of complement activation and nonspecifically by various compounds including endogenous peptides, endorphins, and enkephalins. In >30% of CU patients, autoimmune phenomena have been found, characterized by positive autologous serum skin test, antibodies to the alpha-subunit of the basophil IgE receptor, to IgE itself, and, perhaps, the most clinically relevant, thyroid autoimmunity. Studies suggest that the products of the activated immune system can lower the cutaneous mast cell release threshold, possibly allowing activation by endogenous compounds. The resulting release of mediators produces the clinical picture of recurrent hives. Although the goal of management of CU is the identification of a treatable cause, in most CU patients, especially adults, a cause is not frequently found. Identified causes include drugs, foods, infections, immune complex production leading to urticarial vasculitis, autoantibody production, and underlying autoimmune disease, particularly autoimmune thyroiditis. The treatment of the thyroiditis with suppressive doses of thyroid hormone often results in the remission of the CU. Given the marginally effective and sometimes dangerous medical therapy available for CU, a systematic and thorough approach to identify a treatable cause in difficult CU patients is warranted.

Chronic urticaria and thyroid disease.

Because the association of thyroid disease with pruritus and urticaria dates back more than 50 years, many investigators have commented on the possible link between autoimmune thyroid disease and chronic urticaria. This article summarizes an evolving body of literature linking these two conditions and discusses potential mechanisms as to how they concomitantly occur. Treatment options used to manage and control the urticaria are discussed with a focus on how the thyroid gland may have a role in the possible mechanism leading to chronic urticaria in this setting and how thyroid hormone may contribute to resolution of this condition.

La reacción anafiláctica / The anaphylactic reaction

Una persona alérgica a la penicilina, al veneno de insectos o determinado alimento generalmente no es consciente de su problema hasta el momento en que se presentan los síntomas. Un médico con experiencia puede reconocer la reacción y darle tratamiento antes que la situaciónes torne peligrosa para la vida. Este artículo revisa las características de la reacción anafiláctica, el diagnóstico diferencial y el tratamiento del episodio agudo. Y el tratamiento del episodio agudo. Se hace énfasis en la prevención de la exposición repetida al agente desencadenante, ya que el paciente presenta un mayor riesgo de anafilaxia después de la primera reacción.