He suffered from infancy from great fragility of health, and nearly died in 1858 of gastric fever, which left much constitutional weakness behind it.
The death of Lowell's mother, and the fragility of his wife's health, led Lowell, with his wife, their daughter Mabel and their infant son Walter, to go to Europe in 1851, and they went direct to Italy.
These include thin translucent skin, arterial/intestinal/uterine fragility or rupture, extensive bruising, and characteristic facial appearance.
These include generally loose joints, low muscle tone at birth, scoliosis at birth (which worsens with age), and a fragility of the eyes, which may give the white area of the eye a blue tint or cause the eye to rupture.
In a condition known as purpura simplex, there is a tendency to bruise easily due to an increased fragility of the blood vessels.