Webster's New World Medical Dictionary

hypothyroidism, congenital
See 
cretinism.
hypothyroidism, infantile
Underactivity of the
thyroid gland that starts after birth in infancy or
early childhood, as manifested by delays in growth
and development, and by myxedema (a dry, waxy
type of swelling, often including swollen lips and
nose). Treatment involves use of thyroid hormone
medication. Also known as Brissaud infantilism and
infantile myxedema.
hypotonia
Decreased muscle tone and strength
that results in floppiness. Hypotonia is a common
finding with cerebral palsy and other neuromuscu-
lar disorders. Untreated hypotonia can lead to hip
dislocation and other problems. Treatment is via
physical therapy. In some cases, braces may be
needed to permit a full range of movement in
patients with hypotonia.
hypotonic solution
A solution that contains
fewer dissolved particles (such as salt and other
electrolytes) than is found in normal cells and
blood. Hypotonic solutions are commonly used to
give fluids intravenously to hospitalized patients in
order to treat or avoid dehydration.
hypoventilation
The state in which a reduced
amount of air enters the alveoli in the lungs, result-
ing in decreased levels of oxygen and increased lev-
els of carbon dioxide in the blood. Hypoventilation
can be due to breathing that is too shallow (hypop-
nea) or too slow (bradypnea), or to diminished lung
function. The opposite of hypoventilation is hyper-
ventilation (overbreathing).
hypovolemia
Abnormal decrease in the volume
of blood plasma. Hypovolemia occurs with dehy-
dration or bleeding.
hypovolemic shock
See 
shock, hypovolemic.
hypoxia
A lower-than-normal concentration of
oxygen in arterial blood, as opposed to anoxia, a
complete lack of blood oxygen. Hypoxia will occur
with any interruption of normal respiration.