It is difficult to say how common factitious disorders are. A review of psychiatric consultations in a tertiary care setting found about 1% of referrals received a diagnosis of factitious disorder. Using an entirely different approach, researchers examined specimens submitted by patients as kidney stones and found that 3.5% were obviously non-physiological.

But whatever the prevalence, the consequences can be serious. They include unnecessary diagnostic procedures or interventions and sometimes self-injury.

To find out more about this condition, please do listen to this BMJ Best Practice podcast interview with James Levenson, Professor of Psychiatry at Virginia Commonwealth University. And importantly James is author of our BMJ Best Practice topic on factitious disorders. Competing interests: None

For more on factitious disorders, visit BMJ Best Practice.

Down's syndrome is the most common genetic cause of intellectual disability, occurring in 1 in about 800 births worldwide. Children and adults with Down's syndrome need high quality care from a wide range of different types of healthcare professionals.

To find out more about this condition, listen to this BMJ Best Practice podcast interview with Kishore Vellody, Professor of Pediatrics, University of Pittsburgh School of Medicine. Competing interests: None

For more on Down's Syndrome, visit BMJ Best Practice.

In 2016, the estimated number of people globally with active epilepsy was 45.9 million. For the US in 2015, this figure was around 3.4 million. So epilepsy is common and generalised seizures are a common type of epilepsy.

And the consequences can be serious - from medication side effects to status to sudden unexpected death.

To find out more about this problem and what we can do about it, listen to this BMJ Best Practice podcast interview with Daniel Winkel, Assistant Professor of Neurology at Emory University School of Medicine.

For more on generalised seizures, visit BMJ Best Practice.

Competing interests: DW receives consulting fees from NextSense, Inc.

Measles, mumps and rubella are all serious illnesses. They are also all preventable.

Vaccination is safe and effective. But take up of the vaccine is not what it should be.

To find out more about this problem and what we can do about it, please do listen to this BMJ Best Practice podcast interview with Helen Bedford, Professor of Children's Health at the UCL Institute of Child Health.

For more on these infections, visit BMJ Best Practice.

Competing interests: None

Insomnia is common and can be serious.

It is estimated that 10% to 30% of the population may have insomnia. Insomnia can cause accidents and poor productivity at work. Psychiatric disorders, particularly anxiety and depression, are common comorbidities.

To find out more about this problem and what we can do about it, please do listen to this BMJ Best Practice podcast interview with John Winkelman, Chief of the Sleep Disorders Clinical Research Program, Department of Psychiatry, Massachusetts General Hospital and Professor of Psychiatry, Harvard Medical School.

To find out more about insomnia, visit BMJ Best Practice.

Competing interests: JWW has received honoraria for consulting to Avadel, CVS, Eisai, and Merck, and research grants from Merck and the RLS Foundation.

Hypercholesterolemia is common condition with serious consequences. It is important that we assess, diagnose and manage it appropriately.

To find out more about this problem and what we can do about it, please do listen to this BMJ Best Practice podcast interview with Thorsten Leucker, Assistant Professor of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine.

For more on hypercholesterolemia, visit BMJ Best Practice.

Competing interests: TL has received grant funding for his university from Amgen and Merck.

The purpose of BMJ Best Practice is to provide knowledge that will help healthcare professionals deliver better care. In this podcast, Dr Clare Mock explains how you can put evidence based knowledge into practice to ensure that we achieve high quality and safe healthcare.

Clare is Clinical Engagement Physician at BMJ and has a great deal of experience in safety, quality improvement and implementation science.

Competing interests: CM works for BMJ. 

Hyperkalemia is common and can be serious. It can result in life-threatening cardiac arrhythmias. So it is important that we assess this problem properly, find an underlying diagnosis if there is one, and manage appropriately.

To find out more about this problem and what we can do about it, please do listen to this BMJ Best Practice podcast interview with Sri Yarlagadda, Associate Professor at The University of Kansas Medical Center.

Competing interests: None declared

For more on hyperkalemia, visit BMJ Best Practice.

Hypothyroidism is common. The prevalence of overt hypothyroidism in the general population ranges between 0.2 and 5%. And it can cause a range of complications - from heart to brain problems to problems during pregnancy. So it is important that we get the diagnosis and management of this condition right.

To find out more about this problem and what we can do about it, listen to this interview with Dr Wail Malaty who works as a physician in Houston, Texas. Wail is our BMJ Best Practice author on hypothyroidism. Competing interests: None

For more on hypothyroidism, visit BMJ Best Practice.