Saturday, August 30, 2008

Syndrome X

Syndrome X or Metabolic syndrome:

Metabolic syndrome is also known as metabolic syndrome X, syndrome X, insulin resistance syndrome, Reaven's syndrome

The metabolic syndrome consists of multiple, interrelated risk factors of metabolic origin that appear to directly promote the development of atherosclerotic cardiovascular disease (ASCVD). This constellation of metabolic risk factors is strongly associated with type 2 diabetes mellitus or the risk for this condition.

Diagnostic criteria

Measure (Any 3 of 5 Criteria Constitute Diagnosis of Metabolic Syndrome) Categorical Cut Points
Elevated waist circumference

≥102 cm (≥40 inches) in men

≥88 cm (≥35 inches) in women

Elevated Blood Pressure

≥130 mm Hg systolic BP


≥85 mm Hg diastolic BP


Drug treatment for hypertension

Elevated fasting glucose

≥100 mg/dL


Drug treatment for elevated glucose

Elevated Triglycerides

≥150 mg/dL (1.7 mmol/L)


Drug treatment for elevated TG

Reduced HDL-Cholesterol

<40 mg/dL (1.03 mmol/L) in men

<50 mg/dL (1.3 mmol/L) in women


Drug treatment for reduced HDL-C



  • To measure waist circumference, locate top of right iliac crest. Place a measuring tape in a horizontal plane around the abdomen at level of iliac crest. Before reading tape measure, ensure that tape is snug but does not compress the skin and is parallel to floor. Measurement is made at end of normal expiration.
  • Lower waist circumference cut point (eg, ≥90 cm [35 inches] in men and ≥80 cm [31 inches] in women) appears to be appropriate for Asians.
  • Fibrates and nicotinic acid are the most commonly used drugs for elevated Triglycerides and reduced HDL-C. Patients taking 1of these drugs presumed to have high Triglycerides and low HDL.
  • Abdominal obesity is highly correlated with and easier to measure than other indicators of insulin resistance and as  abdominal obesity incorporates both concepts of obesity and insulin resistance as being the 2 major underlying risk factors of the metabolic syndrome

The primary goal of clinical management of the metabolic syndrome is to reduce risk for clinical atherosclerotic disease.

A closely related goal is to decrease the risk for type 2 diabetes mellitus in those patients who do not yet manifest clinical diabetes.


Syndrome Z = Metabolic Syndrome X + obstructive sleep apnea

Other entities which are also known as Syndrome X:

  1. cardiac syndrome X
  2. Fragile X syndrome

Cardiac syndrome X:

  • Cardiac syndrome X occurs when a patient has all of the symptoms of angina pectoris without coronary artery disease or spasm.

note:Prinzmetal angina or variant angina occurs as a result of transient coronary artery spasms. These spasms can occur either at rest or with exertion.

  • Cardiac syndrome X, the triad of
  1. angina pectoris,
  2. a positive exercise electrocardiogram for myocardial ischaemia and
  3. angiographically smooth coronary arteries
  • The main cause of SX is coronary microvascular dysfunction, as indicated by an abnormal response of coronary microcirculation to both vasoconstrictor and vasodilatory stimuli (microvascular angina)

Fragile X syndrome:

  • the most common form of inherited mental retardation
  • the second-leading cause of genetically associated mental retardation after Down syndrome


The genetic defect is dynamic and lies at the distal end of the long arm of the X chromosome.

Careful examination of the karyotype of affected individuals' lymphocytes, cultured in a folate-depleted and thymidine-depleted medium, reveals a constriction followed by a thin strand of genetic material that extends beyond the long arm at the highly conserved band Xq27.3.

This constriction and thin strand produce the appearance of a fragile portion of the X chromosome, leading to the term fragile X.

The function of fragile X mental retardation (FMR1) gene is believed to play a role in normal brain development.

contains a repeating base pair triplet (CGG) expansion, which is responsible for fragile X syndrome.


  • The phenotype of fragile X syndrome is difficult to diagnose in prepubertal children. Most physical examination findings are notable only after onset of puberty.


    • Growth: Childhood growth is marked by an early growth spurt. However, adult height is often average or slightly below average.
    • Craniofacial: Adolescent and adult patients have a long, thin face with prominent ears, facial asymmetry, a head circumference higher than the 50th percentile, and a prominent forehead and jaw.
  • Ears: Ears are typically large and may protrude.
  • Genitals: Macroorchidism is universal in adult males. In unaffected males, average testicular volume is 17 mL; in patients with fragile X syndrome, testicular volume is more than 25 mL and can be as high as 120 mL.

other physical characteristics can include:

  • Mouth: The mouth has dental overcrowding and a high-arched palate.
  • Eyes: Strabismus is frequently noted.
  • Extremities: Hands and feet manifest nonspecific findings, including hyperextensible finger joints, hand calluses, double-jointed thumbs, a single palmar crease, and pes planus.
  • Back and chest: Pectus excavatum and scoliosis are frequent findings.
  • Cardiac: A heart murmur or click consistent with mitral valve prolapse is often auscultated and requires consultation with a cardiologist.
  • Cognitive history
    • IQ in males frequently indicates mild-to-severe mental retardation (20-70). Females and less-affected males may have IQs that approach 80.

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