Testosterone for the aging male; current evidence and recommended practice

Figures & data

Table 1 Definition of the metabolic syndrome

	WHO	IDF	NCEP III
Essential feature	Diabetes, impaired glucose tolerance or insulin resistancea	Central obesity (men >94 cm waist, women >80 cm waist)	No essential feature
	Essential feature plus 2 from;	Essential feature plus 2 from;	Diagnosis requires three factors from;
Diagnosis requires	Hypertension (>140/90)	Hypertension (>130/85)	Hypertension (>130/85)
	Hypertriglyceridaemia (>1.7 mmol/l)	Hypertriglyceridaemia (>1.7 mmol/l)	Hypertriglyceridaemia (>1.7 mmol/l)
	Low HDL cholesterolb	Low HDL cholesterol (<1.03 mmol/l)	Low HDL cholesterol (<1.03 mmol/l)
	Central obesityc	Raised fasting glucose (>5.6 mmol/l)	Raised fasting glucose (>5.6 mmol/l)
	Microalbuminuriad		Central obesitye

a Impaired glucose tolerance = glucose >7.8 mmol on 2 hour glucose tolerance test. Insulin resistance = in highest quartile of relevant population.

b HDL cholesterol <0.9 mmol/l in men, <1.0 mmol/l in women.

c Waist-hip ratio >0.9 in men, >0.85 in women or BMI greater than 30.

d albumin-creatinine ratio >30.

e Waist circumference >102 cm in men, >88 cm in women.

Abbreviations: WHO, World Health Organisation definition of the metabolic syndrome; IDF, International Diabetes Federation definition of the metabolic syndrome; NCEP, National Cholesterol Education Program Expert Panel III definition of the metabolic syndrome.

Figure 1 The hypogonadal-obesity-adipocytokine cycle hypothesis. Adipose tissue contains the enzyme aromatase which metabolises testosterone to oestrogen. This results in reduced testosterone levels, which increase the action of lipoprotein lipase and increase fat mass, thus increasing aromatisation of testosterone and completing the cycle. Visceral fat also promotes lower testosterone levels by reducing pituitary LH pulse amplitude via leptin and/or other factors. In vitro studies have shown that leptin also inhibits testosterone production directly at the testes. Visceral adiposity could also provide the link between testosterone and insulin resistance (Jones 2007).

Table 2 The advantages and disadvantages of available testosterone preparations with advantages and disadvantages of each

Preparation	Introduced	Advantages	Disadvantages
Subcutaneous pellet	1940s	Cheap Infrequent dosing Physiological levels	Infection around pellet Extrusion of pellet Requires doctor to insert Difficult to reverse treatment
Intramuscular injection (Standard)	1950s	Cheap	Non-physiological levels Fall in levels between injections which may cause symptoms Not usually self administered
Intramuscular injection (Long acting)	2000s	Infrequent dosing Physiological levels	Unable to reverse treatment at short notice Given by nurse Cost
Transdermal patch	1990s	Physiological levels Convenient Self administered	Frequent skin irritation May be unsightly Cost Frequent dosing
Transdermal gel	2000s	Physiological levels Convenient Self administered	Skin irritation Cost Frequent dosing
Buccal tablets	2000s	Physiological levels Convenient Self administered	Presence on gum may irritate Visibility Cost Frequent dosing
Oral testosterone (undecanoate)	1970s	Convenient Self administered	Non-physiological levels Short duration of action Multiple doses needed per day

JonesTHTestosterone associations with erectile dysfunction, diabetes and the metabolic syndromeEur Urol Suppl2007684757

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