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Diabetes Clinical Case Series, Excerpt #8, Endocrinology and Diabetes

CCU_Endocrinology_and_Diabetes

Oliver, aged 46, is found to have an abnormal lipid profile, during routine tests prior to employment abroad.

  • Total cholesterol (TC) 6.5 mmol/L
  • Low density lipoprotein cholesterol (LDL) 5.1 mmol/L
  • High density lipoprotein cholesterol (HDL) 0.9 mmol/L
  • Triglycerides 1.4 mmol/L
  • The patient is asymptomatic.
What would you do?

This patient has high TC, high LDL, high TG and low HDL.

  • High TC and LDL predispose to coronary artery disease
  • Low HDL also predisposes to coronary artery disease
  • The role of high triglycerides in atherosclerotic disease is less defined but high triglycerides are probably also a risk factor, particularly as they are associated with low HDL
  • Very high triglyceride levels can cause pancreatitis

Any associated risk factors should be clarified in this patient, including:

  • Diabetes mellitus
  • Smoking
  • Hypertension
  • Previous history of atherothrombotic disease
  • Family history of ischaemic heart disease
  • Lifestyle issues:
    • Obesity
    • Lack of exercise
    • Alcohol consumption
The patient tells you that:

  • He smokes 10/day
  • His father died of myocardial infarction aged 55
  • He plays football once a week (but not always)
  • He drinks up to 50 units of alcohol a week
  • On examination, his weight is 89 kg (BMI 27) and blood pressure is 169/90 mmHg, and urine dipstick shows protein-, RBC-, WBC-, Glu-, Nit-.
What do these results suggest?

The patient has multiple risk factors for coronary artery disease, including:

  • Family history
  • Smoking
  • Overweight
  • Little physical activity
  • Hypertension
  • Excess alcohol

What tests would you request at this stage?

  • Fasting glucose to rule out the possibility of diabetes
  • TFTs (hypothyroidism is associated with raised cholesterol)
  • U&Es (renal disease is associated with lipid abnormalities, usually low HDL and raised triglyceride)
  • LFTs (cholestatic disease is associated with raised cholesterol)
  • ECG (rule out previous cardiac event or the presence of left ventricular hypertrophy)

Oliver’s tests show:

  • Fasting glucose 5.1 mmol/L
  • FT4 16.7 pmol/L
  • TSH 1.9 mU/L
  • LFTs normal
  • U&Es normal
  • ECG normal
What would you do now?

This patient has multiple risk factors for coronary artery disease and the following issues need to be addressed:

  • Dietary advice
    • Reduce fat in the diet
    • Increase fresh fruit and vegetables
    • Reduce alcohol
  • Weight control through:
    • Diet
    • Exercise: this can increase HDL levels, thereby offering protection from atherosclerotic disease
  • Modification of other risk factors
    • Stop smoking: effective at increasing HDL levels
    • Treat high blood pressure (needs more measurements to confirm)
  • Drug therapy

If the above fails to improve the lipid profile, the following medications can be used:

  • Statins
    • Inhibit cholesterol synthesis in the liver and are very effective at lowering LDL and proven to reduce the risk of coronary artery disease. Most commonly used are pravastatin, simvastatin, atorvastatin and rosuvastatin
  • Ezetimibe
    • Inhibits cholesterol absorption from the gut, usually used as an add-on therapy
  • Fibrates
    • Effective at reducing triglycerides and to a lesser extent cholesterol; usually used as second line
  • Nicotinic acid
    • Effective at increasing HDL and reducing triglyceride levels
  • Bile acid sequestrants
    • Bind to bile acids in the gut inhibiting reabsorption, thereby increasing hepatic cholesterol requirements
    • Very rarely used these days

The decision to start medical treatment for hyperlipidemia can be guided by special tables and computer programs, that take into account associated risk factors.

DCMS178CG1

 

Give one renal cause for high cholesterol with normal U&Es:

  • Nephrotic syndrome can result in hypercholesterolemia
  • Urine dipstick should be performed in all patients with raised cholesterol

Table 40 summarizes the most widely used antihyperlipidaemic agents.

Causes of secondary hyperlipidaemia

These are listed in Table 41.
 

DCMS178CG2

 
 
 

DCMS178CG3

CASE REVIEW:

Oliver, a middle-aged asymptomatic man, was found to have elevated cholesterol (high LDL and low HDL) with normal triglyceride levels during routine tests prior to employment. Both high LDL and low HDL predispose to cardiovascular disease and associated risk factors should be clarified. Other risk factors in this patient include smoking, excess alcohol, obesity, family history of ischemic heart disease and mild hypertension. Subsequent tests rule out diabetes and secondary causes of hypercholesterolemia. Lifestyle modifications are important to reduce the risk of cardiovascular disease, which may improve lipid profile and blood pressure. Antihyperlipidemic agents can be started according to special tables, which offer risk assessment taking into account age, cholesterol levels and associated risk factors.
 

KEY POINTS:

  • Hyperlipidemia is a common condition and can be clinically silent until the development of complications
  • Individuals with raised cholesterol, particularly in the presence of low HDL, are at risk of cardiovascular disease
  • Individuals with raised triglycerides are at additional risk of pancreatitis
  • Associated risk factors should be addressed in individuals with raised cholesterol including:
    • Diabetes mellitus
    • Smoking
    • Hypertension
    • Previous history of atherothrombotic disease
    • Family history of cardiovascular disease
    • Lifestyle issues (obesity, lack of exercise, excess alcohol)
  • Secondary causes of hyperlipidemia include:
    • Obstructive liver pathology
    • Nephrotic syndrome
    • Drugs
    • Pregnancy
  • Management of hyperlipidmia
    • Lifestyle changes are important (stop smoking, reduce weight, increase exercise)
  • Medical treatment should be started after appropriate risk assessment. Currently used drugs include:
    • Statins: effective at lowering cholesterol and proven to reduce the risk of coronary artery disease
    • Ezetimibe: usually used as an add-on therapy to reduce Fibrates: effective at reducing triglycerides and to a lesser extent cholesterol
    • Nicotinic acid: effective at increasing HDL and reducing triglycerides

Ramzi Ajjan, MRCP, Med Sci, PhD, Senior Lecturer and Honorary Consultant in Diabetes and Endocrinology, Department of Health Clinician Scientist, The LIGHT Laboratories, University of Leeds, Leeds, UK
 

A John Wiley & Sons, Ltd., Publication This edition first published 2011 © 2011 by John Wiley & Sons, Ltd.

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