In secondary cases, treatment of the cause, where possible, is indicated. Additionally, treatment for HLH itself is usually required.

While optimal treatment of HLH is still being debated, current treatment regimes usually involve high dose corticosteroids, etoposide and cyclosporin. Intravenous immunoglobulin is also used. Methotrexate and vincristine have also been used. Other medications include cytokine targeted therapy.

An experimental treatment, an anti IFN-gamma monoclonal antibody tentatively named NI-0501, is in clinical trials for treating primary HLH. The FDA awarded breakthrough drug status to NI-0501 in 2016.

The prognosis is guarded with an overall mortality of 50%. Poor prognostic factors included HLH associated with malignancy, with half the patients dying by 1.4 months compared to 22.8 months for non-tumour associated HLH patients.

Secondary HLH in some individuals may be self-limited because patients are able to fully recover after having received only supportive medical treatment (i.e., IV immunoglobulin only). However, long-term remission without the use of cytotoxic and immune-suppressive therapies is unlikely in the majority of adults with HLH and in those with involvement of the central nervous system (brain and/or spinal cord).

Treatment of LPLD has two different objectives: immediate prevention of pancreatitis attacks and long term reduction of cardiovascular disease risk. Treatment is mainly based on medical nutrition therapy to maintain plasma triglyceride concentration below 11,3 mmol/L (1000 mg/dL). Maintenance of triglyceride levels below 22,6 mmol/L (2000 mg/dL) prevents in general from recurrent abdominal pain.

Strict low fat diet and avoidance of simple carbohydrates

Restriction of dietary fat to not more than 20 g/day or 15% of the total energy intake is usually sufficient to reduce plasma triglyceride concentration, although many patients report that to be symptom free a limit of less than 10g/day is optimal. Simple carbohydrates should be avoided as well. Medium-chain triglycerides can be used for cooking, because they are absorbed into the portal vein without becoming incorporated into chylomicrons. Fat-soluble vitamins A, D, E, and K, and minerals should be supplemented in patients with recurrent pancreatitis since they often have deficiencies as a result of malabsorption of fat. However, the diet approach is difficult to sustain for many of the patients.

Lipid lowering drugs

Lipid-lowering agents such as fibrates and omega-3-fatty acids can be used to lower TG levels in LPLD, however those drugs are very often not effective enough to reach treatment goals in LPLD patients. Statins should be considered to lower elevated non-HDL-Cholesterol.

Additional measures are avoidance of agents known to increase endogenous triglyceride levels, such as alcohol, estrogens, diuretics, isotretinoin, anidepressants (e.g. sertraline) and b-adrenergic blocking agents.

Gene therapy

In 2012, the European Commission approved alipogene tiparvovec (Glybera), a gene therapy for adults diagnosed with familial LPLD (confirmed by genetic testing) and suffering from severe or multiple pancreatitis attacks despite dietary fat restrictions. It was the first gene therapy to receive marketing authorization in Europe; it was priced at about $1 million per treatment, and as of 2016, only one person had been treated with it.

Polycythemia (also known as polycythaemia or polyglobulia) is a disease state in which the hematocrit (the volume percentage of red blood cells in the blood) is elevated.

It can be due to an increase in the number of red blood cells ("absolute polycythemia") or to a decrease in the volume of plasma ("relative polycythemia"). Polycythemia is sometimes called erythrocytosis, but the terms are not synonymous, because polycythemia refers to any increase in red blood cells, whereas erythrocytosis only refers to a documented increase of red cell mass.

The emergency treatment of polycythemia (e.g., in hyperviscosity or thrombosis) is by phlebotomy (removal of blood from the circulation). Depending on the underlying cause, phlebotomy may also be used on a regular basis to reduce the hematocrit. Cytostatics such as busulfan and hydroxyurea are sometimes used for long-term management of polycythemia.

Canakinumab has been approved for treatment of HIDS and has shown to be effective. The immunosuppressant drugs etanercept and anakinra have also shown to be effective. Statin drugs might decrease the level of mevalonate and are presently being investigated. A recent single case report highlighted bisphosphonates as a potential therapeutic option.

For treatment of type II, dietary modification is the initial approach, but many patients require treatment with statins (HMG-CoA reductase inhibitors) to reduce cardiovascular risk. If the triglyceride level is markedly raised, fibrates (peroxisome proliferator-activated receptor-alpha agonists) may be preferable due to their beneficial effects. Combination treatment of statins and fibrates, while highly effective, causes a markedly increased risk of myopathy and rhabdomyolysis, so is only done under close supervision. Other agents commonly added to statins are ezetimibe, niacin, and bile acid sequestrants. Dietary supplementation with fish oil is also used to reduce elevated triglycerides, with the greatest effect occurring in patients with the greatest severity. Some evidence exists for benefit of plant sterol-containing products and omega-3 fatty acids.

Secondary polycythemia is caused by either natural or artificial increases in the production of erythropoietin, hence an increased production of erythrocytes. In secondary polycythemia, 6 to 8 million and occasionally 9 million erythrocytes may occur per millimeter of blood. Secondary polycythemia resolves when the underlying cause is treated.

Secondary polycythemia in which the production of erythropoietin increases appropriately is called physiologic polycythemia.

Conditions which may result in a physiologically appropriate polycythemia include:

- Altitude related - This physiologic polycythemia is a normal adaptation to living at high altitudes (see altitude sickness). Many athletes train at high altitude to take advantage of this effect — a legal form of blood doping. Some individuals believe athletes with primary polycythemia may have a competitive advantage due to greater stamina. However, this has yet to be proven due to the multifaceted complications associated with this condition.

- Hypoxic disease-associated - for example in cyanotic heart disease where blood oxygen levels are reduced significantly, may also occur as a result of hypoxic lung disease such as COPD and as a result of chronic obstructive sleep apnea.

- Iatrogenic - Secondary polycythemia can be induced directly by phlebotomy (blood letting) to withdraw some blood, concentrate the erythrocytes, and return them to the body.

- Genetic - Heritable causes of secondary polycythemia also exist and are associated with abnormalities in hemoglobin oxygen release. This includes patients who have a special form of hemoglobin known as Hb Chesapeake, which has a greater inherent affinity for oxygen than normal adult hemoglobin. This reduces oxygen delivery to the kidneys, causing increased erythropoietin production and a resultant polycythemia. Hemoglobin Kempsey also produces a similar clinical picture. These conditions are relatively uncommon.

Conditions where the secondary polycythemia is not as a result of physiologic adaptation and occurs irrespective of body needs include:

- Neoplasms - Renal-cell carcinoma or liver tumors, von Hippel-Lindau disease, and endocrine abnormalities including pheochromocytoma and adrenal adenoma with Cushing's syndrome.

- People whose testosterone levels are high because of the use of anabolic steroids, including athletes who abuse steroids, or people on testosterone replacement for hypogonadism or transgender hormone replacement therapy, as well as people who take erythropoietin, may develop secondary polycythemia.

Currently, there is no specific treatment to correct the LCAT deficiency so therapy is focused on symptom relief. Corneal transplant may be considered for patients presenting with severely impaired vision caused by cholesterol corneal opacities. Dialysis may be required for patients presenting with renal failure, and kidney transplant may be considered.

Statins (or HMG-CoA reductase inhibitors) are commonly used to treat hypercholesterolemia if diet is ineffective. Other agents that may be used include: fibrates, nicotinic acid, and cholestyramine. These, however, are only recommended if statins are not tolerated or in pregnant women. Statins can reduce total cholesterol by about 50% in the majority of people; effects appear similar regardless of the statin used. While statins are effective in decreasing mortality in those who have had previous cardiovascular disease, debate exists over whether or not they are effective in those with high cholesterol but no other health problems. One review did not find a mortality benefit in those at high risk, but without prior cardiovascular disease. Other reviews concluded a mortality benefit does exist. Statins may improve quality of life when used in people without existing cardiovascular disease (i.e. for primary prevention). Statins decrease cholesterol in children with hypercholesterolemia, but no studies as of 2010 show improved clinical outcomes and diet is the mainstay of therapy in childhood. Injectable antibodies against the protein PCSK9 (evolocumab, bococizumab, alirocumab) can reduce LDL cholesterol and have been shown to reduce mortality.

Acne treatment may require oral tetracycline antibiotics or isotretinoin. Treatments directed at tumor necrosis factor (TNF) (infliximab, etanercept) and interleukin-1 (anakinra) have shown a good response in resistant arthritis and pyoderma gangrenosum. Other traditional immunosuppressant treatments for arthritis or pyoderma gangrenosum may also be used.

Both conditions are treated with fibrate drugs, which act on the peroxisome proliferator-activated receptors (PPARs), specifically PPARα, to decrease free fatty acid production. Statin drugs, especially the synthetic statins (atorvastatin and rosuvastatin), can decrease LDL levels by increasing hepatic reuptake of LDL due to increased LDL-receptor expression.

In 2010, the case of a man with unexplained erythrocytosis and perinephric fluid collection as main features was described in the Case Records of the Massachusetts General Hospital. As a consequence two strikingly similar cases were identified and a review of the literature revealed three more patients with similar characteristics.

As of December 2014, a total of 9 patients worldwide with the TEMPI syndrome have been identified (D.B.Sykes, Personal Communication).

In terms of their therapy:

- Untreated: 2 patients

- Velcade alone: 5 patients

- Immediate autologous transplant: 1 patient

- Velcade followed by Velcade/Lenalidomide followed by autologous transplant: 1 patient

The disorder is treated with vasopressin analogs such as Desmopressin. Nonetheless, many times desmopressin alone is not enough to bring under control all the symptoms, and another intervention must be implemented.

Renal failure is the major cause of morbidity and mortality in complete LCAT deficiency, while in partial deficiency (fish eye disease) major cause of morbidity is visual impairment due to corneal opacity. These patients have low HDL cholesterol but surprisingly premature atherosclerosis is not seen. However, there are some reported cases.

Myomatous erythrocytosis syndrome describes an excessive erythrocyte (red blood cells) production, occurring in about 0.5% of individuals affected by uterine leiomyomas (fibroids). This syndrome is believed to be caused by increased erythropoietin (EPO) production by the kidneys or by the leiomyomas themselves.

According to a survey in 2002, alternative medicine was used in an attempt to treat cholesterol by 1.1% of U.S. adults. Consistent with previous surveys, this one found the majority of individuals (55%) used it in conjunction with conventional medicine.

A review of trials of phytosterols and/or phytostanols, average dose 2.15 g/day, reported an average of 9% lowering of LDL-cholesterol. In 2000, the Food and Drug Administration approved the labeling of foods containing specified amounts of phytosterol esters or phytostanol esters as cholesterol-lowering; in 2003, an FDA Interim Health Claim Rule extended that label claim to foods or dietary supplements delivering more than 0.8 g/day of phytosterols or phytostanols. Some researchers, however, are concerned about diet supplementation with plant sterol esters and draw attention to lack of long-term safety data.

Initial treatment is supportive, with the use of agents to treat cholestasis and pruritus, including the following:

- Ursodeoxycholic acid

- Cholestyramine

- Rifampin

- Naloxone, in refractory cases

The partial external biliary diversion (PEBD) procedure is a surgical approach that diverts bile from the gallbladder externally into an ileostomy bag.

Patients should be supplemented with fat-soluble vitamins, and occasionally medium-chain triglycerides in order to improve growth.

When liver synthetic dysfunction is significant, patients should be listed for transplantation. Family members should be tested for PFIC mutations, in order to determine risk of transmission.

Although the FD-causing gene has been identified and it seems to have tissue specific expression, there is no definitive treatment at present.

Treatment of FD remains preventative, symptomatic and supportive. FD does not express itself in a consistent manner. The type and severity of symptoms displayed vary among patients and even at different ages on the same patients. So patients should have specialized individual treatment plans. Medications are used to control vomiting, eye dryness, and blood pressure. There are some commonly needed treatments including:

1. Artificial tears: using eye drops containing artificial tear solutions (methylcellulose)

2. Feeding: Maintenance of adequate nutrition, avoidance of aspiration; thickened formula and different shaped nipples are used for baby.

3. Daily chest physiotherapy (nebulization, bronchodilators, and postural drainage): for Chronic lung disease from recurrent aspiration pneumonia

4. Special drug management of autonomic manifestations such as vomiting: intravenous or rectal diazepam (0.2 mg/kg q3h) and rectal chloral hydrate (30 mg/kg q6h)

5. Protecting the child from injury (coping with decreased taste, temperature and pain perception)

6. Combating orthostatic hypotension: hydration, leg exercise, frequent small meals, a high-salt diet, and drugs such as fludrocortisone.

7. Treatment of orthopedic problems (tibial torsion and spinal curvature)

8. Compensating for labile blood pressures

There is no cure for Familial Dysautonomia.

Familial dysalbuminemic hyperthyroxinemia is a type of hyperthyroxinemia associated with mutations in the human serum albumin gene.

The term was introduced in 1982.

Topical steroid preparations often help outbreaks; use of the weakest corticosteroid that is effective is recommended to help prevent thinning of the skin. Drugs such as antibiotics, antifungals, corticosteroids, dapsone, methotrexate, thalidomide, etretinate, cyclosporine and, most recently, intramuscular alefacept may control the disease but are ineffective for severe chronic or relapsing forms of the disease. Intracutaneous injections of botulinum toxin to inhibit perspiration may be of benefit. Maintaining a healthy weight, avoiding heat and friction of affected areas, and keeping the area clean and dry may help prevent flares.

Some have found relief in laser resurfacing that burns off the top layer of the epidermis, allowing healthy non-affected skin to regrow in its place.

Secondary bacterial, fungal and/or viral infections are common and may exacerbate an outbreak. Some people have found that outbreaks are triggered by certain foods, hormone cycles and stress.

In a few cases naltrexone appears to help.

Apolipoprotein B deficiency (also known as "Familial defective apolipoprotein B-100") is an autosomal dominant disorder resulting from a missense mutation which reduces the affinity of apoB-100 for the low-density lipoprotein receptor (LDL Receptor) . This causes impairments in LDL catabolism, resulting in increased levels of low-density lipoprotein in the blood. The clinical manifestations are similar to diseases produced by mutations of the LDL receptor, such as familial hypercholesterolemia. Treatment may include, niacin or statin or ezetimibe.

It is also known as "normotriglyceridemic hypobetalipoproteinemia".

There is currently no cure for FD and death occurs in 50% of the affected individuals by age 30. There are only two treatment centers, one at New York University Hospital and one at the Sheba Medical Center in Israel. One is being planned for the San Francisco area.

The survival rate and quality of life have increased since the mid-1980s mostly due to a greater understanding of the most dangerous symptoms. At present, FD patients can be expected to function independently if treatment is begun early and major disabilities avoided.

A major issue has been aspiration pneumonia, where food or regurgitated stomach content would be aspirated into the lungs causing infections. Fundoplications (by preventing regurgitation) and gastrostomy tubes (to provide nonoral nutrition) have reduced the frequency of hospitalization.

Other issues which can be treated include FD crises, scoliosis, and various eye conditions due to limited or no tears.

An FD crisis is the body's loss of control of various autonomic nervous system functions including blood pressure, heart rate, and body temperature. Both short-term and chronic periodic high or low blood pressure have consequences and medication is used to stabilize blood pressure.

Familial dysbetalipoproteinemia or type III hyperlipoproteinemia (also known as remnant hyperlipidemia, "remnant hyperlipoproteinaemia", "broad beta disease" and "remnant removal disease") is a condition characterized by increased total cholesterol and triglyceride levels, and decreased HDL levels.

Testing the general population under the age of 40 without symptoms is of unclear benefit.

No treatment is generally required, as bone demineralisation and kidney stones are relatively uncommon in the condition.