Prevention
Croup is contagious during the first few days of the infection. Basic hygiene including hand washing can prevent transmission. There are no vaccines that have been developed to prevent croup, however, many cases of croup have been prevented by immunization for influenza and diphtheria. At one time, croup referred to a diphtherial disease, but with vaccination, diphtheria is now rare in the developed world. Treatment
Most children with croup have mild symptoms and supportive care at home is effective. For children with moderate to severe croup, treatment with corticosteroids and nebulized epinephrine may be suggested. Steroids are given routinely, with epinephrine used in severe cases. Children with oxygen saturation less than 92% should receive oxygen, and those with severe croup may be hospitalized for observation. In very rare severe cases of croup that result in respiratory failure, emergency intubation and ventilation may be required. With treatment, less than 0.2% of children require endotracheal intubation. Since croup is usually a viral disease, antibiotics are not used unless secondary bacterial infection is suspected. The use of cough medicines, which usually contain dextromethorphan or guaifenesin, are also discouraged. Supportive care
Supportive care for children with croup includes resting and keeping the child hydrated. Infections that are mild are suggested to be treated at home. Croup is contagious so washing hands is important. Children with croup should generally be kept as calm as possible. Over the counter medications for pain and fever may be helpful to keep the child comfortable.
The LDL is typically above the 75th percentile, that is, 75% of the healthy population would have a lower LDL level. Cholesterol levels can be drastically higher in people with FH who are also obese. Mutation analysis
On the basis of the isolated high LDL and clinical criteria (which differ by country), genetic testing for LDL receptor mutations and ApoB mutations can be performed. Mutations are detected in between 50 and 80% of cases; those without a mutation often have higher triglyceride levels and may in fact have other causes for their high cholesterol, such as combined hyperlipidemia due to metabolic syndrome. Differential diagnosis
FH needs to be distinguished from familial combined hyperlipidemia and polygenic hypercholesterolemia. Lipid levels and the presence of xanthomata can confirm the diagnosis. Sitosterolemia and cerebrotendineous xanthomatosis are two rare conditions that can also present with premature atherosclerosis and xanthomas. The latter condition can also involve neurological or psychiatric manifestations, cataracts, diarrhea and skeletal abnormalities. Genetics
The most common genetic defects in FH are LDLR mutations (prevalence 1 in 250, depending on the population), ApoB mutations (prevalence 1 in 1000), PCSK9 mutations (less than 1 in 2500) and LDLRAP1. The related disease sitosterolemia, which has many similarities with FH and also features cholesterol accumulation in tissues, is due to ABCG5 and ABCG8 mutations. LDL receptor
The LDL receptor gene is located on the short arm of chromosome 19 (19p13.1-13.3). It comprises 18 exons and spans 45 kb, and the protein gene product contains 839 amino acids in mature form.