All About Testosterone

SummaryThe male hormone, testosterone, is responsible for muscle strength and weight control in both men and women. Testosterone in our body peaks around the age of 25-30, and then continuously declines. This age related decline is main reason why we gain weight, loose muscle strength, feel anxious and tired. It is one of the most commonly abused hormones among athletes to make up for the age related muscle decline. Increased weight, diabetes, and other health conditions can abnormally affect levels which can further compound these problems. Once diagnosed, it is relatively easy to monitor and correct for low testosterone levels. A simple saliva test (with an at home testosterone test kit), without requiring any needles, can measure free testosterone levels in the body. This article will discuss details about this key hormone, the natural decline with age, how one can test for testosterone, and how it can be maintained naturally.


What is Testosterone?

Testosterone is a hormone that both in men and women produce, although we commonly associate it with male sexual health. It is responsible for muscle strength, bone mass, and fat distribution in our body, especially around the waist.

T production levels peak around age 25 before starting to decline. This decline is part of the natural aging process, falling about 1% per year as we age. Because it helps repair muscle tissues, it is one of the most commonly used hormones by athletes to build muscles and make up for this age related muscle decline.


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Low T levels can lead to weight gain, decreased muscle strength, anxiety, and fatigue. In old people, the low levels make men ‘cranky’, disinterested, and less sociable. The increased weight, diabetes, and other health conditions can negatively affect the levels, which can further compound these problems.

It is relatively easy to test for testosterone levels. An at home kit using a saliva sample can accurately determine your levels. The test measures free testosterone which is a better predictor of biologically active form in the body. The test is relatively inexpensive and one can do it from the comfort of home by shipping the samples to a lab. Besides the convenience and confidentiality it offers, the biggest advantage of the test is eliminating the need for a blood draw. That’s especially important for those afraid of needles.

Once diagnosed, it is easy to monitor and correct for low testosterone. However, this should be done after discussion with a physician as the FDA warns that there are risks of heart attacks and strokes associated with products used for correcting low testosterone levels.


Important properties of testosterone:


  • Leydig cells in testicles and ovaries produce the male hormone
  • Testosterone belongs to the family of male hormones known as Androgens (others androgen hormones include: DHEA, Androstenedione)
  • It is a type of anabolic hormone, which promotes tissue generation by turning on genes that make muscles grow. Athletes often use it for tissue growth and recovery despite some controversy; especially useful for cancer patients & victims of starvation)
  • Testosterone is a type of steroid hormone (uses a 4-ring “steroid” nucleus backbone); other steroid hormones are: estrogen, progesterone, cortisol, Vitamin D, androstenediones, aldosterone, DHEA-S, pregnenolone
  • Derived from cholesterol


Testosterone levels by age

What are the key issues related to testosterone changes?


  • Low T levels decrease sexual drive
  • Higher levels of male hormone increase aggression
  • Low T can decrease muscle size and strength; increases body fat; also can contribute to fatigue and chronic tiredness
  • Lower levels can result in thinning of bones, cholesterol problems, and high risk of heart disease – conditions that compound the problem with aging
  • Testosterone is the ‘crankiness hormone’: low levels can affect the mood resulting in anxiety and depression, low zest for life, and reduced tendency to socialize


Why is testosterone popular among athletes?


  • Androgens (or anabolic steroids) are popular among athletes for muscle build up and regular muscle maintenance
  • Body builders take male hormone for strong muscle build up


What is hypogonadism or low-T problem?


  • T levels starts to drop around age 25 as part of normal aging process
  • But any abrupt drop or abnormal levels for that age level can cause deficiency, termed as hypogonadism


What are the symptoms of low testosterone or hypogonadism?


  1. The most common symptoms of low levels in men are related to reduced sexual performance (or erectile dysfunction); they can have erection but results in low quality of sex or less frequently or can not maintain as long as before; it can also result in poor response to medications such as Viagra or Cialis
  2. Male hormone deficiency results in decreased libido due to its impact on the brain, which regulates the sex drive
  3. Low T results in weight gain (especially around the middle) due to increase in fat & reduction in muscle mass; it also causes slower metabolism and less desire to exercise
  4. Low T results in muscle weakness and loss of endurance; less tendency to play sports
  5. Fatigue, low energy, frequently falling asleep after dinner (fatigue can be due by low muscle strength, poor sleep, depression, and anemia — testosterone affects all these conditions)
  6. Depression or anxiety, changes in mood, nervousness, and low sense of well being; higher irritability, anger, or negative thinking, poor response to anti-depressant medications; feeling terrible & no interest in life (stereotypical characteristics of aging that match with low T symptoms in men)
  7. Decreased quality of life and sense of well-being
  8. Insomnia, that can add to fatigue
  9. Poor memory and lack of concentration beyond normal age related decline & can impact work performance
  10. Premature aging resulting in look and feel of being older than actual age
  11. Male breast growth in men, especially in obese men
  12. Bone problem due to thinning of bones which can result in hip, wrist or spine fracture and a strong reason for medical practitioners to recommend therapy; it converts to estrogen and this process needs to slow down to help bone strength
  13. Joint problems which result in aches and pains in joints
  14. High blood pressure
  15. Sensation of warmth, flashes, and excessive sweating in the night (somewhat similar to menopause)
  16. Anemia due to low red blood cell production from reduced levels
  17. Decreased frequency of shaving as male hormone is related to hair growth
  18. Loss of body hair including chest, pubic, and armpit hair
  19. Dry, flaky, and thinner skin as male hormone regulates the amount of oil produced by skin
  20. Male fertility problems, e.g., low ejaculate volume, poor sperm count (T, LH, FSH hormones are needed for normal sperm production)
  21. Softening or shrinking of testicles
  22. Softening of voice with more feminine sound


What are the causes of low testosterone?


  1. Most common cause of low T is the natural age related decline
  2. Trauma or injury to testicles where the hormone is produced
  3. Urological conditions that can block blood supply to cells producing it
  4. Complications of vasectomy
  5. Head injury that might affect pituitary glands
  6. Diabetes – which can both affect male hormone and can be affected by it as well; Type 1 diabetes patients generally tend to have a high rate of deficiency; combination of age-related androgen decline, excess weight, chronic illness, high blood pressure, and insulin resistance can cause a vicious cycle of low T and high blood sugar; diabetes patients tend to have more SHBG (sex hormone-bounding globulin) that increases the bound, inactive form making the total T level normal but the free, active form may be low
  7. Obesity increases testosterone controlling hormones (leptin, cortisol, inflammatory kytokines or adipokines) that signal the brain for lower T production and thus lower muscle mass and more fat; this creates a vicious cycle of further reducing levels in body; increased weight increases aromatose–the enzyme converting testosterone into estrogen, thus making less of the it available for muscle mass & fat control
  8. Infections of testicles (Orchitis), mumps, and HIV can cause lower T
  9. Immune system problems, such as Type 1 diabetes and autoimmune thyroid diseases attack body to reduce levels
  10. Hereditary Hemochromatosis (HH) is a genetic disorder that causes too much iron which can block pancreas and pituitary glands resulting in lower T
  11. Sarcoidosis, which are granulomas formed in the body & when formed in brain they can affect hypothalamus and pituitary gland (mostly genetic and tend to be more prevalent in African Americans)
  12. Alcohol is one of the most common cause of damage to testicles; tobacco, marijuana, cocaine, heroine, and narcotic medications can affect hypothalamus and pituitary gland
  13. Excess cortisol can lower the levels
  14. Fluid retention in the body can cut-off blood supply to testicles; can result in kidney, liver, or heart problems
  15. Chronic pain increases cortisol levels and insulin resistance resulting in lower testosterone
  16. Radiation and chemotherapy can impact hypothalamus & pituitary glands
  17. Liver diseases can result in higher estrogen and thus lower T levels
  18. Exposure to female hormones, e.g., estrogen creams from spouse
  19. Any other problem related to the brain & pituitary glands


Testosterone levels in women

It is also important for women as it plays a key role in maintaining muscle mass, bone density, and weight control. Women have about 10 times lower levels than men. High levels of testosterone in women can result in:


  • too much facial hair
  • increased muscle mass and low body fat content
  • deepening of voice and smaller breasts
  • irregular or absent menstrual cycle
  • fertility problems, especially polycystic ovary syndrome (PCOS) that makes it difficult to get pregnant
  • in some case, high testosterone can result in acne in women


What are different forms of testosterone?

Testosterone is measured in three different forms in a test depending on how it is bound in the blood:


All About Testosterone

a. Measured free T: not bound and therefore affected by SHBG. There are two blood tests available:

i. Equilibrium dialysis – more accurate method for free & total T, but expensive
ii. Analog method – cheap, easy but not as reliable
b. Calculated free T: calculated from the total T, SHBG & albumin values; sometimes more accurate than measured free T as it combines best of both worlds


It is also important to understand the SHBG (Sex hormone-binding globulin) results in certain cases:

i. if normal – total will be normal
ii. Is abnormal, especially low – surely there is a problem
iii. If high – total T may appear normal but can be low; needs further analysis


  1. Total Testosterone: it includes all the available male hormone in the body, and has three different parts: free testosterone (about 2%) + testosterone bound to SHBG protein (60-80%) + testosterone bound to albumin (20-40%). Whatever is bound to SHBG is not active. Therefore, total testosterone is not the best indicator of healthy levels.
  2. Free Testosterone: not bound to protein & is the better indicator of levels of testosterone; it is the dialyzable portion; it can either be measured or calculated:


The Harvard Men’s Health Watch provides an excellent description of total and free testosterone.


How to get tested for low testosterone?


  • A blood or saliva sample can measure testosterone levels
  • A saliva test is simple and less stressful than a blood test while providing equivalent or sometimes even superior results; saliva test is a new technique and not yet as widely known as blood test; saliva test is equivalent measurement of free testosterone, the most active of the three types
  • For blood test, the venipuncture using needles for blood draw can cause adrenal stress in children and those afraid of needles
  • A saliva sample measures free testosterone, the most active form, thus providing reliable results
  • The main concern with saliva test is variations in results; however, at-home health test from CLIA-certified labs that regularly compare their results with others can provide highly reproducible and reliable results
  • Several scientific studies have shown saliva test can deliver equivalent and even better results, including this scientific review from the journal of Clinical Chemistry and this study on 1500 males between 20 and 90 years old


It is recommended to provide samples in the morning, around 7-10 am, within 30 minutes of waking up when the T levels are highest. Note that testosterone is age dependent and therefore should be compared against a reference of same age group.

Saliva based testosterone test

  1. Only free Testosterone available in the saliva is tested (not affected by SHBG & albumin protein bound T)
  2. Need to ensure the lab has a history of reliable testing with clearly defined ranges
  3. Not susceptible to any temporary fluctuations due to the stress induced by fear of needles in blood test

As an example, testosterone levels in saliva test for a 40 year old male (highly dependent on age) will be:

  • 50 pg/ml: low level requiring further attention (hypogonadism, low-t problems)
  • 50 – 185 pg/ml: normal range
  • 185 pg/ml: high levels that also need attention (due to higher aggression and other concerns)


Blood based testosterone test

The traditional method of testosterone testing. The ranges for the blood test are:

  • Normal range is: 260 – 1000 ng/dL
  • if < 500 ng/dL – low and may need attention
  • < 300 ng/dL – needs treatment


What are the challenges to testosterone testing?


  1. Test reliability – easier to measure high T than low T (but most people want to know if they have low T)
  2. Lab imperfections – assay variability & different reference ranges from lab-to-lab; one reason why it’s highly recommended to use labs that are (1) CLIA certified labs, (2) test thousands to samples with well defined ranges, and (3) regularly compare their data with other labs across the country; all three conditions are met by our at-home testosterone test
  3. Hormone flexes – highest in the morning (reason why men tend to get erection in the morning); if morning is low, very high chance of low T; sometimes the recommendation is to measure 3 or 4 samples from the same day at different times
  4. Blood proteins – for blood tests, 98% of T is attached to protein & only about 2% is free T; 60-80% attached to SHBG and is biologically inactive, 20-40% is bound to a protein called albumin where it can become free & biologically active
  5. Variation due to individuals and age
  6. The blood test results may have an impact from sudden stress—from the fear of needles


Other key information relevant to testosterone testing


  • Tightly bound to T (60 – 80%)
  • Normal SHBG: reliable for total T measurement
  • Low or high: can’t predict T
  • Increases with aging



  • 20 – 40% of T is weekly bound and is bioavailable T
  • Less important for measurement
  • Abnormal levels are rare
  • Measured during a standard blood test for metabolism


DHT (dihydrotestosterone):

  • Testosterone converts to DHT (by 5-alpha-reductase)
  • Used for high T issue diagnosis; can result in hair loss and prostate enlargement



  • High levels of Estrogen (and estrone and estriol) result in low T
  • High levels can be due to liver problem, obesity, or accidental exposure from women’s prescriptions


Is there a diagnosis for low testosterone?


  • Medical professionals prescribe Testosterone Replacement Test (TRT) to those with low T to achieve normal levels
  • There is no pill – as TRT pills cause liver toxicity
  • Common methods are gel, injections, or chewable prescriptions
  • Low T causes low red blood count resulting in anemia; however, TRT may sometimes cause too much blood & needs to be monitored for blood count and prostate growth


Testosterone levels by age

What are the natural ways of increasing Testosterone?


  • Exercise: makes muscles physically and metabolically stronger; one of the best ways to increase your levels and balance other hormones
  • Weight training: increases muscle mass and metabolism; highly recommended natural way to increase levels; medical professionals recommend 30 minutes of weight training at least twice a week
  • Stress relief: stress lowers testosterone and other androgens; low T slow down metabolism resulting in reduced muscle mass and increased body fat
  • Vitamin D: although critical for bone health, it is equally important for muscles; lower Vitamin D results in tired, flabby, and weak muscles (Vitamin deficiency increases over age & data suggest more than half of US elders are below recommended Vitamin D levels)
  • Sleep time: our body secretes hormones while sleeping; without enough sleep body can’t produce enough
  • Growth hormone (GH): since GH is important for muscle growth, any deficiency will result in low testosterone symptoms
  • Insufficient proteins: since proteins are the building blocks of healthy muscles, low protein levels in diet will impact testosterone levels


Source: Hormone Balance by Scott Isaacs, MD


Other references:

  1. Learn from the experts at Mayo Clinic about Male Hypogonadism:: Symptoms & causes | Diagnosis & treatment
  2. Also see the Mayo Clinic’s page: Testosterone therapy: Potential benefits and risks as you age
  3. From Harvard Men’s Health Watch, read about the complexity of symptoms of low T, details on different ‘kinds’ of testosterones, what are normal testosterone levels, and how even experienced physicians have differing opinions on how to get tested for low T: Testing your testosterone: It’s tricky.
  4. In our review of key literature on testosterone, please also read: Testosterone vs parenting:Men’s relationship status, fatherhood, and how invested they are in paternal care significantly impact their testosterone levels
  5. After testing, see your physician for next steps; there is an increased risk of heart attacks and strokes from using testosterone as outlined by the FDA Drug Safety Communication.


Disclaimer: For information purposes only—not to be used for diagnosis or to replace advice from a medical professional. An At Home Testosterone Test can be ordered here. Information on other health tests can be found here. You can order a CLIA-certified at-home health test from anytime for free shipping and physician-approved reports.