The list of signs and symptoms mentioned in various sources for Sub clinical hypothyroidism includes the 18 symptoms listed below: 1  Fatigue, loss of energy, lethargy. 2  Weight gain. 3  Decreased appetite. 4  Cold intolerance. 5  Dry skin. 6  Hair loss. 7  Sleepiness. 8  Muscle pain, joint pain, weakness in the extremities. 9  Depression.