An 18-year-old girl presented with dyspnea and diffuse cellulitis in the abdomen and both legs. She had been born at 40 weeks by cesarean section with a birth weight of 1.9 kg. Typical hypotonia and poor oral intake during infancy had been noted in the patient, which was followed by rapid weight gain and intellectual disability during childhood. The diagnosis of PWS was made at 14 years of age, and the paternal deletion was identified through methylation test and fluorescence
in situ hybridization for 15q11-q13. Growth hormone (GH) therapy could not be applied due to the patient's advanced bone age (over 14 years) at that time. Her intelligence quotient was measured as 30, and type 2 DM and hypertension were diagnosed when she was 16 years old and were treated with metformin and a calcium channel blocker, respectively. The patient's parents tried to limit her food intake, and her daily calorie intake was approximately 1,600 kcal. At the time of the visit, the patient's height, weight, and BMI were 143 cm (-3.8 standard deviation score [SDS]), 145 kg (4.5 SDS), and 71 kg/m
2, respectively (
Table 1). Her vital signs were 190/100 mmHg, 115 beats/min, 24 breaths/min, and 36℃ body temperature. She was unable to walk or sit unaided due to joint pain and massive cellulitis in the abdomen and legs (
Fig. 1A, B). Before the hospital visit, her body weight had increased rapidly by 20 kg due to reduced physical activity for the previous 2 weeks. Ampicillin/sulbactam was administered for cellulitis, and her daily calorie intake was restricted to 800 kcal/day for 1 week; however, her body weight increased to 164 kg (4.7 SDS), and her dyspnea was aggravated. The patient was put on mechanical ventilation for 20 days, and her calorie intake was restricted to 200 kcal/day. Furosemide (40 mg every 8 hours) and fluid restriction (1000 mL/day, 5% dextrose with 600-mL electrolytes and 400-mL free water) were used to induce a massive bodyweight reduction. After loss of 26 kg, extubation was successfully performed. The patient's electrolytes had been closely monitored and balanced (Na, 135–142 mEq/L; K, 3.3–4.0 mEq/L) during the weight reduction process. A pituitary function test was performed due to primary amenorrhea, which revealed hypopituitarism, including GH and gonadotropin deficiencies. Low dosages of GH (1.33 IU/day) and estrogen (0.125 mg/day) were therefore administered. In addition to the high dosage of metformin (1,500 mg/day), a GLP-1 receptor agonist (Liraglutide, Victoza, Novo Nordisk, Denmark) was added for appetite reduction. The serum glycosylated hemoglobin (HbA1c) level was observed as 7.3%. The GLP-1 agonist dosage was initiated at 0.6 mg/day and increased to 1.2 mg/day without an adverse event. In addition, physical therapy, including aerobic exercise and pulmonary rehabilitation, was implemented for 60 minutes per day, 5 days/wk. At the time of discharge (3 months after admission), the patient was able to walk independently, and her weight and BMI had decreased to 104 kg and 50.8 kg/m
2, respectively (
Table 1). The HbA1c level was reduced from 7.3% to 4.8% during these 3 months. After 1 year, the patient's BMI was maintained at 48.5 kg/m
2, and she was satisfied on a diet of 1,000 kcal/day diet comprised of carbohydrates (100 g), proteins (48 g), and fat (42 g). In addition, regular mealtimes and expected food amounts were maintained. The patient had continued to exercise daily for 1 hour with familial support. After 1 year, a waist circumference reduction (7 cm), weight loss (62.7 kg), and BMI reduction (31.7 kg/m
2) were noted (
Fig. 2).