Table 2. Differential Diagnosis of Secondary Hyper-LDL cholesterolemia.

disease name	Points of differentiation
Nephrotic syndrome	Increased cholesterol and apoprotein synthesis in the liver. Edema is observed. It is important to check proteinuria and serum albumin levels.
Obesity	Measure height, weight, percentage of body fat, waist circumference, etc. and correctly evaluate the degree of obesity. High TG and low HDL-C occurs mainly by visceral fat accumulation. LDL-C also tend to be high.
Hypothyroidism	Systemic metabolic function decreases. Hyper-LDL cholesterolemia is caused by decreased expression and activity of the LDL receptor. Because Hashimoto’s disease is common, autoantibodies should be measured.
Anorexia nervosa	The patient presents with a high degree of emaciation. Low T3 syndrome leading to hyper-LDL cholesterolemia. Sex hormones and other factors are also suppressed.
Diabetes mellitus	Diagnosis is based on blood glucose and HbA1c levels. Hyper-LDL cholesterolemia, hypertriglyceridemia, and hypo-HDL cholesterolemia are often seen. Diabetes is a major risk for atherosclerotic disease, and glycemic control alone has little preventive effect.
Cushing’s syndrome	Excessive cortisol secretion promotes VLDL synthesis in the liver, resulting in hyper-LDL cholesterolemia. In children, the disease is characterized by weight gain without height growth and early onset of puberty due to androgen excess.
Pheochromocytoma	Excessive secretion of catecholamines promotes VLDL synthesis in the liver, resulting in hyper-LDL cholesterolemia. Suspected when symptoms such as headache, palpitations, sweating, and hypertension (paroxysmal or persistent) are present.
Diet related (excessive intake of cholesterol)	Excessive cholesterol intake may cause hyper-LDL cholesterolemia. In particular, if breastfeeding results in marked hyper-LDL cholesterolemia, the child should be retested after weaning to differentiate from sitosterolemia. Examine for the presence of xanthomas.
Cholestatic liver disease	FH-like hyper-LDL cholesterolemia may occur with biliary atresia and cholestatic liver disease.
Drug-induced (steroids, cyclosporin, etc.)	The diagnosis and treatment can be made by with drawal or reduction of the suspected drug.