Yes
Yes
Yes
Yes
Yes
Lethargy is basically a state of being tired or lazy. It is a very vague symptom, and though can occur in narcotic abuse, is not specific enough by itself to be of much value.
Hypernatremia is especially dangerous for children and the elderly
Severe hypernatremia has a mortality rate of 40-60%
Hypernatremia can cause neurological damage due to shrinkage of brain cells
Severe hypernatremia, with serum sodium above 152 mM, can result in seizures and death
yes
Many cancers don't have many symptoms. My father had kidney cancer and lethargy seemed to be a symptom. Nausea as well may be an indicator. Check with a doctor.
Ber beri is caused by deficiency of vitamin B1. It causes weakness, lethargy, swelling of the body, mental confusion and breathing difficulty due to heart failure.