Hypothyroidism refers to the common pathological condition of thyroid hormone deficiency. The annual incidence of hypothyroidism is 3.5 per 1000 in women and 0.6 in per 1000 men. Hypothyroidism is seen 5-8 times more frequently in women than in men. Patients with hypothyroidism have a higher prevalence of cardiovascular risk factors and often have metabolic syndrome features such as hypertension, increased waist circumference, and dyslipidemia. Other signs and symptoms include bradycardia, slow speech, swelling in the eyes and face, weight gain, decreased sweating, hair loss, pallor, forgetfulness, decreased concentration, depression, irritability, tongue growth, loss of appetite, palpitations, decreased hearing, menstrual irregularities, muscle pains, and cramps. Depending on all these signs and symptoms, hypothyroidism can negatively affect the quality of life of individuals. Therefore, it is essential to reduce symptoms and to improve patients' abilities to manage them. It is stated that the appropriate use of mobile health applications helps the patient to make informed decisions about health management and treatment. Therefore, this study plans to investigate the effect of mobile technology on symptom management in individuals with hypothyroidism, whose symptoms range from mild to severe.

The research will be carried out in Sakarya University Training and Research Hospital Endocrinology Polyclinic. It is planned to include a total of 80 patients in the research (40 patients in the control group - 40 patients in the experiment group). The first step of this study is to develop the scales to be used in the study. The Hypothyroidism Symptom Management Scale and the Hypothyroidism Symptom Severity Scale will be developed. In the second stage, data will be collected. The Patient Information Form, Hypothyroidism Symptom Severity Scale, and Hypothyroidism Symptom Management Scale will be applied to the experimental group that meets the research criteria and agrees to participate. The patient's blood test findings (TSH, T3, T4, Anti-Tg, Anti TPO, Antithyroglobulin, Hmg, Hct) will also be recorded at the first meeting. The researcher will measure the patient's height, weight, and vital signs. The mobile application will be introduced to the patients and downloaded to the patient's phones, and a username and password will be created. The content of this mobile application; Interventions will be planned based on evidence-based practices to alleviate or reduce the symptoms of hypothyroidism. These initiatives are planned both in written form and in short video narration. Patients will be asked to watch the videos in the mobile application for the first week. At the end of each week, patients will be asked to report symptoms in the application and read and follow the recommendations for the relevant symptom. The usage period of the mobile application is determined as three months (12 weeks). In addition, at the end of the fourth week, patients will be followed up by having the symptom management scale and symptom severity scale applied via the mobile application. In the 6th and 12th weeks, evaluations of the patient's laboratory test results, vital signs, height, and weight measurements, will also be evaluated besides the scales. In the first interview with the individuals in the control group, after explanations are made about the research and their verbal and written consents are accordingly obtained, First, the Patient Information Form, the Hypothyroidism Symptom Severity Scale, and the Hypothyroidism Symptom Management Scale will be administered as a pre-test. At the first interview, the patient's blood test findings, height, weight, and vital signs will be recorded. Measurements will be repeated when individuals come to their outpatient clinic appointments 6 and 12 weeks after the first interview.

Inclusion Criteria:

• Able to communicate,
• Who agrees to participate in the study,
• Able to use a mobile phone with android or ıos (iPhone os) operating system
• No vision and dexterity problems,
• Without communication difficulties and cognitive impairment,
• Literate
• Being diagnosed with hypothyroidism

Exclusion Criteria:

• Pregnant patients,
• Those with a diagnosed psychiatric illness,
• Those who use antidepressants,
• Patients who experienced trauma or an acute illness during the study (12 weeks)